add {{TEST_MINIO_ENDPOINT}} for local testing "with/without" docker + fix pgsql testi...

add {{TEST_MINIO_ENDPOINT}} for local testing "with/without" docker + fix pgsql testing doc (#32105)

while testing i found out that testing locally as documented in the
changed README.md for pgsql isn't working because of the minio
dependency. reworked this to by default be still docker, but allow for
for local with only minio in docker and testing on bare metal.
also depending on this: fixed docs for running pgsql test

Closes: #32168 (by changing documentation for pgsql tests)
Closes: #32169 (by changing documentation, Makefile & pgsql.ini.tmpl:
adding {{TEST_MINIO_ENDPOINT}})

sry for the combined pr, but when testing I ran into this issue and
first thought they were related and now finally address the same
problem: not beeing able to run pgsql integration tests as described in
the according README.md