pgsql: Add regression test for background worker restart after crash.

Add regression test for background worker restart after crash.

Previously, if a background worker crashed and the server restarted
with restart_after_crash enabled, the worker was not restarted
as expected. This issue was fixed by commit b5d084c5353,
which ensures that background workers without the never-restart flag
are correctly restarted after a crash-and-restart cycle.

To guard against regressions, this commit adds a test that verifies
a background worker successfully restarts in such a scenario.

Author: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Reviewed-by: ChangAo Chen <cca5507(at)qq(dot)com>
Discussion: https://postgr.es/m/CAHGQGwHF-PdUOgiXCH_8K5qBm8b13h0Qt=dSoFXZybXQdbf-tw@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/cc321b1d1c55fe208a394b0f8e0e99c5fb91742c

Modified Files
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src/test/recovery/t/013_crash_restart.pl | 7 +++++++
1 file changed, 7 insertions(+)