tests: Rename conflicting role names

tests: Rename conflicting role names

These cause problems when running installcheck-world USE_MODULE_DB=1 with -j.

Note: This patch has been originally applied to v16 and newer branches
as of 6a20b04f0408.  Sami Imseih has reported this issue as being
possible to reach for other branches still supported: REL_15_STABLE and
REL_14_STABLE.

Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/20221003234111.4ob7yph6r4g4ywhu@awork3.anarazel.de
Discussion: https://postgr.es/m/CAA5RZ0soPHUvwXLZ+mf5Q=uJRL5ggnRg1uB0qKVG1bbdA9up6w@mail.gmail.com
Backpatch-through: 14