pgsql: Fix the logical replication from HEAD to lower versions.

Fix the logical replication from HEAD to lower versions.

Commit 464824323e changed the logical replication protocol to allow the
streaming of in-progress transactions and used the new version of protocol
irrespective of the server version. Use the appropriate version of the
protocol based on the server version.

Reported-by: Ashutosh Sharma
Author: Dilip Kumar
Reviewed-by: Ashutosh Sharma and Amit Kapila
Discussion: https://postgr.es/m/CAE9k0P=9OpXcNrcU5Gsvd5MZ8GFpiN833vNHzX6Uc=8+h1ft1Q@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/079d0cacf4fefc326bf776ecc2df5dba995f50de

Modified Files
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src/backend/replication/logical/worker.c    | 4 +++-
src/backend/replication/pgoutput/pgoutput.c | 4 ++--
src/include/replication/logicalproto.h      | 8 +++++---
3 files changed, 10 insertions(+), 6 deletions(-)