ci: Fix cached MacPorts installation management

1.  The error reporting of "port setrequested list-of-packages..."
changed, hiding errors we were relying on to know if all packages in our
list were already installed.  Use a loop instead.

2.  The cached MacPorts installation was shared between PostgreSQL
major branches, though each branch wanted different packages.  Add the
list of packages to cache key, so that different branches, when tested
in one github account/repo such as postgres/postgres, stop fighting with
each other, adding and removing packages.

Back-patch to 15 where CI began.

Author: Thomas Munro <thomas.munro@gmail.com>
Author: Nazir Bilal Yavuz <byavuz81@gmail.com>
Suggested-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/au2uqfuy2nf43nwy2txmc5t2emhwij7kzupygto3d2ffgtrdgr%40ckvrlwyflnh2

.cirrus.tasks.yml

@@ -427,6 +427,20 @@ task:
     CCACHE_DIR: ${HOME}/ccache
     MACPORTS_CACHE: ${HOME}/macports-cache
 
+    MACOS_PACKAGE_LIST: >-
+      ccache
+      icu
+      kerberos5
+      lz4
+      meson
+      openldap
+      openssl
+      p5.34-io-tty
+      p5.34-ipc-run
+      python312
+      tcl
+      zstd
+
     CC: ccache cc
     CXX: ccache c++
     CFLAGS: -Og -ggdb
@@ -463,26 +477,14 @@ task:
   macports_cache:
     folder: ${MACPORTS_CACHE}
     fingerprint_script: |
-      # Include the OS major version in the cache key.  If the OS image changes
-      # to a different major version, we need to reinstall.
+      # Reinstall packages if the OS major version, the list of the packages
+      # to install or the MacPorts install script changes.
       sw_vers -productVersion | sed 's/\..*//'
-      # Also start afresh if we change our MacPorts install script.
+      echo $MACOS_PACKAGE_LIST
       md5 src/tools/ci/ci_macports_packages.sh
     reupload_on_changes: true
   setup_additional_packages_script: |
-    sh src/tools/ci/ci_macports_packages.sh \
-      ccache \
-      icu \
-      kerberos5 \
-      lz4 \
-      meson \
-      openldap \
-      openssl \
-      p5.34-io-tty \
-      p5.34-ipc-run \
-      python312 \
-      tcl \
-      zstd
+    sh src/tools/ci/ci_macports_packages.sh $MACOS_PACKAGE_LIST
     # system python doesn't provide headers
     sudo /opt/local/bin/port select python3 python312
     # Make macports install visible for subsequent steps