pgsql: ci: Change macOS builds from Intel to ARM.

ci: Change macOS builds from Intel to ARM.

Cirrus is about to shut down its macOS-on-Intel support, so it's time to
move our CI testing over to ARM instances.  The Homebrew package manager
changed its default installation prefix for the new architecture, so a
couple of tests need tweaks to find binaries.

Back-patch to 15, where in-tree CI began.

Author: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/20221122225744.GF11463%40telsasoft.com

Branch
------
REL_15_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/dc513bc6544dd7f49a1c2d3bf06c77dbc2b5c9c3

Modified Files
--------------
.cirrus.yml                     | 8 ++++----
src/test/kerberos/t/001_auth.pl | 9 ++++++++-
src/test/ldap/t/001_auth.pl     | 8 +++++++-
3 files changed, 19 insertions(+), 6 deletions(-)