pgsql: Add more LOG and DEBUG messages for slot synchronization.

Add more LOG and DEBUG messages for slot synchronization.

This provides more information about remote slots during synchronization
which helps in debugging bugs and BF failures due to test case issues. We
might later want to change the LOG message added by this patch to DEBUG1.

Author: Hou Zhijie
Reviewed-by: Amit Kapila, Bertrand Drouvot
Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com
Discussion: https://postgr.es/m/OS0PR01MB571633C23B2A4CAC5FB0371A944C2@OS0PR01MB5716.jpnprd01.prod.outlook.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7a424ece4828fa107f36e1c77985eabdbe69e50b

Modified Files
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src/backend/replication/logical/slotsync.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)