Use YAML anchors and aliases to reduce workflow repetition

Author: eddyashton

.github/workflows/long-test.yml

@@ -15,7 +15,7 @@ permissions: read-all
 
 jobs:
   long-asan:
-    if: ${{ contains(github.event.pull_request.labels.*.name, 'run-long-test') || github.event_name == 'workflow_dispatch' || github.event_name == 'schedule'}}
+    if: &check_trigger_conditions ${{ contains(github.event.pull_request.labels.*.name, 'run-long-test') || github.event_name == 'workflow_dispatch' || github.event_name == 'schedule'}}
     name: "ASAN"
     runs-on:
       [
@@ -75,7 +75,7 @@ jobs:
           if-no-files-found: ignore
 
   long-tsan:
-    if: ${{ contains(github.event.pull_request.labels.*.name, 'run-long-test') || github.event_name == 'workflow_dispatch' || github.event_name == 'schedule'}}
+    if: *check_trigger_conditions
     name: "TSAN"
     runs-on:
       [
@@ -138,7 +138,7 @@ jobs:
   # - Sanitizer builds may slightly differ.
   # - Test durations may also differ, which is important for -L "suite" because they have fixed timeouts.
   long-e2e-debug:
-    if: ${{ contains(github.event.pull_request.labels.*.name, 'run-long-test') || github.event_name == 'workflow_dispatch' || github.event_name == 'schedule'}}
+    if: *check_trigger_conditions
     name: Long e2e - Debug
     runs-on:
       [
@@ -201,7 +201,7 @@ jobs:
 
   # All e2e tests in release mode (same as release build).
   long-e2e-release:
-    if: ${{ contains(github.event.pull_request.labels.*.name, 'run-long-test') || github.event_name == 'workflow_dispatch' || github.event_name == 'schedule'}}
+    if: *check_trigger_conditions
     name: Long e2e - Release
     runs-on:
       [
@@ -265,7 +265,7 @@ jobs:
   # - Long LTS tests
   # - Ensure snmalloc linkage
   e2e-long-combined:
-    if: ${{ contains(github.event.pull_request.labels.*.name, 'run-long-test') || github.event_name == 'workflow_dispatch' || github.event_name == 'schedule'}}
+    if: *check_trigger_conditions
     name: Long Shuffled/LTS/Snmalloc
     runs-on:
       [