pgsql: Fix instability in 026_overwrite_contrecord.pl test.

Fix instability in 026_overwrite_contrecord.pl test.

We've seen intermittent failures in this test on slower buildfarm
machines, which I think can be explained by assuming that autovacuum
emitted some additional WAL.  Disable autovacuum to stabilize it.

In passing, use stringwise not numeric comparison to compare
WAL file names.  Doesn't matter at present, but they are
hex strings not decimal ...

Discussion: https://postgr.es/m/1372189.1636499287@sss.pgh.pa.us

Branch
------
REL_13_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/5a3240cf6b2e9f5fb6befe7e1ac4c0c0464ce3d2

Modified Files
--------------
src/test/recovery/t/026_overwrite_contrecord.pl | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)