pgsql: Fix oauth validator test on EXEC_BACKEND

Fix oauth validator test on EXEC_BACKEND

Commit 8e54a414570010af included a test for invalidated oauth validator
with a SKIP stanza for EXEC_BACKEND Windows builds, but failed to handle
non-Windows EXEC_BACKEND builds. Since the debug GUC for retrieveing the
EXEC_BACKEND state is only available since, we add an alternative output
to capture the failure on EXEC_BACKEND. Per buildfarm member culicidae.

Author: Daniel Gustafsson <daniel(at)yesql(dot)se>
Reported-by: Jacob Champion <jacob(dot)champion(at)enterprisedb(dot)com>
Discussion: https://postgr.es/m/C6EE5C79-AC29-4F3D-B0BD-B07E9298051A@yesql.se

Branch
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REL_18_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/dcf112bd4e4cfe1651fafe169dffdaf076bd0b43

Modified Files
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src/test/modules/oauth_validator/t/001_server.pl | 22 ++++++++--------------
1 file changed, 8 insertions(+), 14 deletions(-)