Log prefix missing for subscriber log messages received from publisher

Hi,

Currently, when a warning is emitted by the publisher, the
corresponding log message does not include the log prefix. This makes
it harder to correlate such messages with other log entries. For
example, in a simulated error scenario where directory removal fails,
the notice message lacks the standard log prefix, as shown below:
2025-03-18 16:44:36.071 IST [196901] LOG:  logical replication table
synchronization worker for subscription "sub1", table "t1" has
finished
WARNING:  could not remove directory
"pg_replslot/pg_16398_sync_16387_7483106341004194035.tmp"

In this case, the WARNING line does not include the usual timestamp
information, making it harder to trace.

To address this, we can have a custom notice processor for WAL
receiver connections—similar to what's done in the attached patch.
This ensures that notices received during both streaming and logical
replication include the appropriate log prefix. Since this issue is
present in both replication modes, the patch sets the notice processor
for all WAL receiver connections.

Regards,
Vignesh