Remove catalyst changes

I believe scripts/test_catalyst.sh needs to change. Since many workflow files use it, I'll do a
separate catalyst PR.

Author: ncooke3

.github/workflows/sessions.yml

@@ -127,14 +127,12 @@ jobs:
     # Don't run on private repo unless it is a PR.
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request'
 
-    runs-on: macos-15
+    runs-on: macos-14
     steps:
     - uses: actions/checkout@v4
     - uses: mikehardy/buildcache-action@c87cea0ccd718971d6cc39e672c4f26815b6c126
       with:
         cache_key: catalyst${{ matrix.os }}
-    - name: Xcode
-      run: sudo xcode-select -s /Applications/Xcode_16.2.app/Contents/Developer
     - uses: ruby/setup-ruby@354a1ad156761f5ee2b7b13fa8e09943a5e8d252 # v1
     - name: Setup Bundler
       run: scripts/setup_bundler.sh