pgsql: Prevent 006_transfer_modes.pl from leaving files behind.

Prevent 006_transfer_modes.pl from leaving files behind.

This test was leaving files like delete_old_cluster.{sh,bat} in the
source directory for VPATH and meson builds. To fix, change the
directory to tmp_check before running the test, as was done in
commits 15b6d21553, 8af917be6b, and c462b054ba.

Oversight in commit af0d4901c1.

Reported-by: Andrew Dunstan <andrew(at)dunslane(dot)net> (on Discord)
Reviewed-by: Michael Paquier <michael(at)paquier(dot)xyz>
Reviewed-by: Andrew Dunstan <andrew(at)dunslane(dot)net>
Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Discussion: https://postgr.es/m/Z_RHkG770w3SE0yU%40nathan

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b0a4c3e88b8b527679216dca5e2e9cbd49514e99

Modified Files
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src/bin/pg_upgrade/t/006_transfer_modes.pl | 5 +++++
1 file changed, 5 insertions(+)