… reset (#13315)

this PR fixes two crashes:

1. Fix missing slotToKeyInit() when using `flushdb async` under cluster
mode.
    #13205

2. Fix missing expires_cursor reset when stopping active defrag in the
middle of defragment.
    #13307
If we stop active defrag in the middle of defragging db->expires, if
`expires_cursor` is not reset to 0, the next time we enable active
defrag again, defragLaterStep(db, ...) will be entered. However, at this
time, `db` has been reset to NULL, which results in crash.

The affected code were removed by #11695 and #13058 in usntable, so we
just need backport this to 7.2.

Fix #13612
This bug was introduced by #11465

This PR added the incremental defragmentation for db->expires.
If the time for the defragmentation cycle has not arrived, it will exit
unless both cursor and expires_cursor are 0, meaning both keys and
expires have been fragmented.
However, the expires_cursor check has now been overlooked, which leads
to we will exit immediately even if the defragmentation doesn't reach
the end time, which will cause the efficiency of defragmentation to
become very low.

Note that this bug was already fixed in version
7.4(#13058)

This PR fixes two defrag issues.

1. Fix a use-after-free issue caused by updating dictionary keys after a
pubsub channel is reallocated.
This issue was introduced by #13058

1. Fix potential use-after-free for lua during AOF loading with defrag
This issue was introduced by #13058
   This fix follows #14319
This PR updates the LuaScript LRU list before script execution to
prevent accessing a potentially invalidated pointer after long-running
scripts.

After redis#13013

### This PR make effort to defrag the pubsub kvstore in the following
ways:

1. Till now server.pubsub(shard)_channels only share channel name obj
with the first subscribed client, now change it so that the clients and
the pubsub kvstore share the channel name robj.
This would save a lot of memory when there are many subscribers to the
same channel.
It also means that we only need to defrag the channel name robj in the
pubsub kvstore, and then update
all client references for the current channel, avoiding the need to
iterate through all the clients to do the same things.
    
2. Refactor the code to defragment pubsub(shard) in the same way as
defragment of keys and EXPIRES, with the exception that we only
defragment pubsub(without shard) when slot is zero.


### Other
Fix an overlook in redis#11695, if defragment doesn't reach the end time, we
should wait for the current
db's keys and expires, pubsub and pubsubshard to finish before leaving,
now it's possible to exit
early when the keys are defragmented.

---------

Co-authored-by: oranagra <[email protected]>

This PR fixes two defrag issues.

1. Fix a use-after-free issue caused by updating dictionary keys after a
pubsub channel is reallocated.
This issue was introduced by redis#13058

1. Fix potential use-after-free for lua during AOF loading with defrag
This issue was introduced by redis#13058
   This fix follows redis#14319
This PR updates the LuaScript LRU list before script execution to
prevent accessing a potentially invalidated pointer after long-running
scripts.

This PR fixes two defrag issues.

1. Fix a use-after-free issue caused by updating dictionary keys after a
pubsub channel is reallocated.
This issue was introduced by redis#13058

1. Fix potential use-after-free for lua during AOF loading with defrag
This issue was introduced by redis#13058
   This fix follows redis#14319
This PR updates the LuaScript LRU list before script execution to
prevent accessing a potentially invalidated pointer after long-running
scripts.

This PR fixes two defrag issues.

1. Fix a use-after-free issue caused by updating dictionary keys after a
pubsub channel is reallocated.
This issue was introduced by redis#13058

2. Fix potential use-after-free for lua during AOF loading with defrag
This issue was introduced by redis#13058
   This fix follows redis#14319
This PR updates the LuaScript LRU list before script execution to
prevent accessing a potentially invalidated pointer after long-running
scripts.