Make MR Silicon jobs less optional and Intel jobs more optional

Silicon jobs are now cheap enough to be pocket change even when there are no cache hits and can often be useful
while the manual Intel jobs should not be blocking and are typically not useful unless the MR explicitly attempts CI changes

Author: Capostrophic

.gitlab-ci.yml

@@ -553,8 +553,8 @@ Ubuntu_GCC_integration_tests_asan:
   rules:
     - if: $CI_PROJECT_ID != "7107382"
       when: never
-    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
-      when: manual
+    # Merge request event rule is architecture-specific
+    # Unlike ARM64, AMD64 job is manual non-blocking as it's seldom useful
     - if: $CI_PIPELINE_SOURCE == "push" || $CI_PIPELINE_SOURCE == "schedule"
   image: macos-15-xcode-16
   tags:
@@ -593,6 +593,11 @@ Ubuntu_GCC_integration_tests_asan:
 
 macOS15_Xcode16_amd64:
   extends: .MacOS
+  rules:
+    - !reference [.MacOS, rules]
+    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
+      when: manual
+      allow_failure: true
   cache:
     key:
       prefix: macOS15_Xcode16_amd64.v3
@@ -610,6 +615,9 @@ macOS15_Xcode16_amd64:
 
 macOS15_Xcode16_arm64:
   extends: .MacOS
+  rules:
+    - !reference [.MacOS, rules]
+    - if: $CI_PIPELINE_SOURCE == "merge_request_event"
   cache:
     key:
       prefix: macOS15_Xcode16_arm64.v3