This case is interesting because it originates from cron,
rather than from another command.

The idea came from looking at #9890 and #10573, and I was wondering if RM_Call
would work properly when `server.current_client == NULL`

…edis#10573)

RM_Yield was missing a call to protectClient to prevent redis from
processing future commands of the yielding client.

Adding tests that fail without this fix.

This would be complicated to solve since nested calls to RM_Call used to
replace the current_client variable with the module temp client.

It looks like it's no longer necessary to do that, since it was added
back in redis#9890 to solve two issues, both already gone:
1. call to CONFIG SET maxmemory could trigger a module hook calling
   RM_Call. although this specific issue is gone, arguably other hooks
   like keyspace notification, can do the same.
2. an assertion in lookupKey that checks the current command of the
   current client, introduced in redis#9572 and removed in redis#10248

This case is interesting because it originates from cron,
rather than from another command.

The idea came from looking at redis#9890 and redis#10573, and I was wondering if RM_Call
would work properly when `server.current_client == NULL`