Thread: pgsql: Fix cross-version upgrade tests.

Fix cross-version upgrade tests.

TestUpgradeXversion knows how to make the main regression database's
references to pg_regress.so be version-independent.  But it doesn't
do that for plperl's database, so that the C function added by
commit b7e3a52a8 is causing cross-version upgrade test failures.
Path of least resistance is to just drop the function at the end
of the new test.

In <= v14, also take the opportunity to clean up the generated
test files.

Security: CVE-2024-10979

Branch
------
REL_17_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/8d19f3fea003b1f744516b84cbdb0097ae7b2912

Modified Files
--------------
src/pl/plperl/expected/plperl_env.out | 2 ++
src/pl/plperl/sql/plperl_env.sql      | 3 +++
2 files changed, 5 insertions(+)