…_updater_test

68018e4 test: Avoid excessive locking of `cs_wallet` (Hennadii Stepanov)
7986faf test: Fix segfault in the psbt_wallet_tests/psbt_updater_test (Hennadii Stepanov)

Pull request description:

  The dcd6eeb commit (bitcoin#23288) introduced an intermittent failure in the `psbt_wallet_tests/psbt_updater_test` unit test. See bitcoin#23368.

  The test failure can be easily made reproducible with the following patch:
  ```diff
  --- a/src/scheduler.cpp
  +++ b/src/scheduler.cpp
  @@ -57,6 +57,8 @@ void CScheduler::serviceQueue()
               Function f = taskQueue.begin()->second;
               taskQueue.erase(taskQueue.begin());

  +            UninterruptibleSleep(100ms);
  +
               {
                   // Unlock before calling f, so it can reschedule itself or another task
                   // without deadlocking:
  ```

  This PR implements an idea which was mentioned in the [comment](bitcoin#23368 (comment)):
  > Yes, as I said before this looks like a race where the wallet is deleted before stopping the scheduler: [bitcoin#23368 (comment)](bitcoin#23368 (comment))
  >
  > IIRC, the order should be:
  >
  >    * stop scheduler
  >
  >    * delete wallet
  >
  >    * delete scheduler

  The second commit introduces a refactoring with no behavior change.

  Fixes bitcoin#23368.

ACKs for top commit:
  mjdietzx:
    Code review ACK 68018e4

Tree-SHA512: d9103f6252aab807453628159dec243bc543a2595eecaa04ec761dca3c2370085592c55d6f50967d69a4ac6e8b5827eec30dd9b025132c99b0bb9aa5911ad915

459e208 Exit early for an empty vChecks in CCheckQueue::Add (Hennadii Stepanov)
c43aa62 Avoid excessive lock contention in CCheckQueue::Add (Hennadii Stepanov)

Pull request description:

  This PR significantly reduces lock contention in the `CCheckQueue` class by releasing a mutex before calling `std::condition_variable::notify_one` and `std::condition_variable::notify_all`.

  From C++ [docs](https://en.cppreference.com/w/cpp/thread/condition_variable/notify_one):
  > The notifying thread does not need to hold the lock on the same mutex as the one held by the waiting thread(s); in fact doing so is a pessimization, since the notified thread would immediately block again, waiting for the notifying thread to release the lock.

  Related to:
  - #23167
  - #23223

ACKs for top commit:
  martinus:
    ACK 459e208, codereview and tested. I first thought this introduced a segfault in `psbt_wallet_tests/psbt_updater_test` because that test failed for me, but thats a different issue fixed in #23403.
  vasild:
    ACK 459e208
  theStack:
    Code-review ACK 459e208

Tree-SHA512: c197858656392ba3ebcd638d713cf93c9fb48b7b3bad193209490d2828f9c7e3ae4dee6f84674f2f34dceed894139562e29579ee7299e06756c8c990caddc5ed

459e208 Exit early for an empty vChecks in CCheckQueue::Add (Hennadii Stepanov)
c43aa62 Avoid excessive lock contention in CCheckQueue::Add (Hennadii Stepanov)

Pull request description:

  This PR significantly reduces lock contention in the `CCheckQueue` class by releasing a mutex before calling `std::condition_variable::notify_one` and `std::condition_variable::notify_all`.

  From C++ [docs](https://en.cppreference.com/w/cpp/thread/condition_variable/notify_one):
  > The notifying thread does not need to hold the lock on the same mutex as the one held by the waiting thread(s); in fact doing so is a pessimization, since the notified thread would immediately block again, waiting for the notifying thread to release the lock.

  Related to:
  - bitcoin#23167
  - bitcoin#23223

ACKs for top commit:
  martinus:
    ACK 459e208, codereview and tested. I first thought this introduced a segfault in `psbt_wallet_tests/psbt_updater_test` because that test failed for me, but thats a different issue fixed in bitcoin#23403.
  vasild:
    ACK 459e208
  theStack:
    Code-review ACK 459e208

Tree-SHA512: c197858656392ba3ebcd638d713cf93c9fb48b7b3bad193209490d2828f9c7e3ae4dee6f84674f2f34dceed894139562e29579ee7299e06756c8c990caddc5ed

…scheduler

Summary:
> The order should be:
>  - stop scheduler
>  - delete wallet
>  - delete scheduler

This is a partial backport of [[bitcoin/bitcoin#23403 | core#23403]]
bitcoin/bitcoin@68018e4

The other commit in that pull request is not applicable to Bitcoin ABC, for now. It has a dependency on [[bitcoin/bitcoin#23288 | core#23288]], which has itself a lot of dependencies on recent descriptor wallets developments.

Test Plan:
With TSAN:
`ninja && ninja check`

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10883

459e208 Exit early for an empty vChecks in CCheckQueue::Add (Hennadii Stepanov)
c43aa62 Avoid excessive lock contention in CCheckQueue::Add (Hennadii Stepanov)

Pull request description:

  This PR significantly reduces lock contention in the `CCheckQueue` class by releasing a mutex before calling `std::condition_variable::notify_one` and `std::condition_variable::notify_all`.

  From C++ [docs](https://en.cppreference.com/w/cpp/thread/condition_variable/notify_one):
  > The notifying thread does not need to hold the lock on the same mutex as the one held by the waiting thread(s); in fact doing so is a pessimization, since the notified thread would immediately block again, waiting for the notifying thread to release the lock.

  Related to:
  - bitcoin#23167
  - bitcoin#23223

ACKs for top commit:
  martinus:
    ACK 459e208, codereview and tested. I first thought this introduced a segfault in `psbt_wallet_tests/psbt_updater_test` because that test failed for me, but thats a different issue fixed in bitcoin#23403.
  vasild:
    ACK 459e208
  theStack:
    Code-review ACK 459e208

Tree-SHA512: c197858656392ba3ebcd638d713cf93c9fb48b7b3bad193209490d2828f9c7e3ae4dee6f84674f2f34dceed894139562e29579ee7299e06756c8c990caddc5ed