pgsql: Refactor replorigin_session_setup() for better readability.

Refactor replorigin_session_setup() for better readability.

Reorder the validation checks in replorigin_session_setup() to provide a
more logical flow. This makes the function easier to follow and ensures
that basic state checks are performed consistently.

Additionally, update an error message to align its phrasing with similar
diagnostics in the replication origin subsystem, improving overall
consistency.

Author: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-by: shveta malik <shveta.malik@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://postgr.es/m/e0508305-bc6a-417c-b969-36564d632f9e@iki.fi

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/735e8fe685359480e77d837493a5dc0a38866944

Modified Files
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src/backend/replication/logical/origin.c | 79 +++++++++++++++++++-------------
1 file changed, 47 insertions(+), 32 deletions(-)