pgsql: Make 030_pg_recvlogical robust against PID reuse

Make 030_pg_recvlogical robust against PID reuse

The reconnection test assumed that a restarted walsender would always
have a different PID from the previous one. On some platforms, however,
PIDs can be reused quickly, causing the test to time out even though
pg_recvlogical has successfully reconnected.

This issue was reported by buildfarm member fairywren:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=fairywren&dt=2026-07-30%2009%3A58%3A12

Fix this by waiting for the server log message indicating that the
logical replication slot has been acquired again, rather than relying on
a PID change.

Backpatch to v19, where the affected reconnection test was introduced by
commit d89b1d817513.

Author: Hayato Kuroda <kuroda(dot)hayato(at)fujitsu(dot)com>
Reviewed-by: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Discussion: https://postgr.es/m/OS9PR01MB121497CF10DFF54F745E37204F5C92@OS9PR01MB12149.jpnprd01.prod.outlook.com
Backpatch-through: 19

Branch
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REL_19_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/cacba321c2ef9dfd1c1b6924b6c7291a1182d2d6

Modified Files
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src/bin/pg_basebackup/t/030_pg_recvlogical.pl | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)