pgsql: Fix instance of elog() called while holding a spinlock

Fix instance of elog() called while holding a spinlock

This broke the project rule to not call any complex code while a
spinlock is held. Issue introduced by b89e151.

Discussion: /messages/by-id/20200602.161518.1399689010416646074.horikyota.ntt@gmail.com
Backpatch-through: 9.5

Branch
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REL_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/03aa25b6e34b5f5184cfd0df71f1096c66523b72

Modified Files
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src/backend/replication/logical/logical.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)