Fix drone_dimensions. (#126953)

Use drone_dimensions instead of dimensions for builds running on dart-internal. This is required for those builders to select the correct drone type.

.ci.yaml

@@ -347,6 +347,8 @@ targets:
       firebase_project: master-docs-flutter-dev
       release_ref: refs/heads/master
       release_build: "true"
+    drone_dimensions:
+      - os=Linux
 
   - name: Linux docs_test
     recipe: flutter/flutter
@@ -4833,8 +4835,8 @@ targets:
       task_name: flutter_packaging
       tags: >
         ["framework", "hostonly", "shard", "linux"]
-    dimensions:
+    drone_dimensions:
-      os: "Linux"
+      - os=Linux
 
   - name: Mac flutter_packaging
     recipe: packaging/packaging
@@ -4847,9 +4849,9 @@ targets:
       task_name: flutter_packaging
       tags: >
         ["framework", "hostonly", "shard", "mac"]
-    dimensions:
+    drone_dimensions:
-      cpu: "x86"
+      - os=Mac
-      os: "Mac"
+      - cpu=x86
 
 
   - name: Mac_arm64 flutter_packaging
@@ -4863,9 +4865,9 @@ targets:
       task_name: flutter_packaging
       tags: >
         ["framework", "hostonly", "shard", "mac"]
-    dimensions:
+    drone_dimensions:
-      cpu: "arm64"
+      - os=Mac
-      os: "Mac"
+      - cpu=arm64
 
   - name: Windows flutter_packaging
     recipe: packaging/packaging
@@ -4879,8 +4881,8 @@ targets:
       task_name: flutter_packaging
       tags: >
         ["framework", "hostonly", "shard", "windows"]
-    dimensions:
+    drone_dimensions:
-      os: "Windows"
+      - os=Windows
 
 
   - name: Linux docs_deploy_beta
@@ -4903,8 +4905,8 @@ targets:
       validation: docs_deploy
       validation_name: Docs_deploy
       firebase_project: master-docs-flutter-dev
-    dimensions:
+    drone_dimensions:
-      os: "Linux"
+      - os=Linux
 
   - name: Linux docs_deploy_stable
     recipe: flutter/flutter
@@ -4926,5 +4928,5 @@ targets:
       validation: docs_deploy
       validation_name: Docs_deploy
       firebase_project: docs-flutter-dev
-    dimensions:
+    drone_dimensions:
-      os: "Linux"
+      - os=Linux