Re-apply "switch to the macos-12-xl builder"

This reverts commit e63ec2e140.

.github/workflows/ci.yml

@@ -322,7 +322,7 @@ jobs:
               NO_DEBUG_ASSERTIONS: 1
               NO_OVERFLOW_CHECKS: 1
               DIST_REQUIRE_ALL_TOOLS: 1
-            os: macos-latest
+            os: macos-12-xl
           - name: dist-apple-various
             env:
               SCRIPT: "./x.py dist bootstrap --include-default-paths --host='' --target=aarch64-apple-ios,x86_64-apple-ios,aarch64-apple-ios-sim"
@@ -333,7 +333,7 @@ jobs:
               NO_LLVM_ASSERTIONS: 1
               NO_DEBUG_ASSERTIONS: 1
               NO_OVERFLOW_CHECKS: 1
-            os: macos-latest
+            os: macos-12-xl
           - name: dist-x86_64-apple-alt
             env:
               SCRIPT: "./x.py dist bootstrap --include-default-paths"
@@ -344,7 +344,7 @@ jobs:
               NO_LLVM_ASSERTIONS: 1
               NO_DEBUG_ASSERTIONS: 1
               NO_OVERFLOW_CHECKS: 1
-            os: macos-latest
+            os: macos-12-xl
           - name: x86_64-apple-1
             env:
               SCRIPT: "./x.py --stage 2 test --exclude tests/ui --exclude tests/rustdoc --exclude tests/run-make-fulldeps"
@@ -355,7 +355,7 @@ jobs:
               NO_LLVM_ASSERTIONS: 1
               NO_DEBUG_ASSERTIONS: 1
               NO_OVERFLOW_CHECKS: 1
-            os: macos-latest
+            os: macos-12-xl
           - name: x86_64-apple-2
             env:
               SCRIPT: "./x.py --stage 2 test tests/ui tests/rustdoc tests/run-make-fulldeps"
@@ -366,7 +366,7 @@ jobs:
               NO_LLVM_ASSERTIONS: 1
               NO_DEBUG_ASSERTIONS: 1
               NO_OVERFLOW_CHECKS: 1
-            os: macos-latest
+            os: macos-12-xl
           - name: dist-aarch64-apple
             env:
               SCRIPT: "./x.py dist bootstrap --include-default-paths --stage 2"
@@ -381,7 +381,7 @@ jobs:
               NO_OVERFLOW_CHECKS: 1
               DIST_REQUIRE_ALL_TOOLS: 1
               JEMALLOC_SYS_WITH_LG_PAGE: 14
-            os: macos-latest
+            os: macos-12-xl
           - name: x86_64-msvc-1
             env:
               RUST_CONFIGURE_ARGS: "--build=x86_64-pc-windows-msvc --enable-profiler"

src/ci/github-actions/ci.yml

@@ -78,7 +78,7 @@ x--expand-yaml-anchors--remove:
     <<: *base-job
 
   - &job-macos-xl
-    os: macos-latest  # We don't have an XL builder for this
+    os: macos-12-xl
     <<: *base-job
 
   - &job-windows-xl