Use variable instead of container resource in AZP (#80299)

.azure-pipelines/azure-pipelines.yml

@@ -30,11 +30,8 @@ variables:
     value: .azure-pipelines/commands/entry-point.sh
   - name: fetchDepth
     value: 500
-
-resources:
-  containers:
-    - container: default
-      image: quay.io/ansible/azure-pipelines-test-container:3.0.0
+  - name: defaultContainer
+    value: quay.io/ansible/azure-pipelines-test-container:3.0.0
 
 pool: Standard
 

.azure-pipelines/templates/coverage.yml

@@ -6,7 +6,7 @@
 jobs:
   - job: Coverage
     displayName: Code Coverage
-    container: default
+    container: $[ variables.defaultContainer ]
     workspace:
       clean: all
     steps:

.azure-pipelines/templates/test.yml

@@ -11,7 +11,7 @@ jobs:
   - ${{ each job in parameters.jobs }}:
     - job: test_${{ replace(replace(replace(replace(job.test, '/', '_'), '.', '_'), '-', '_'), '@', '_') }}
       displayName: ${{ job.name }}
-      container: default
+      container: $[ variables.defaultContainer ]
       workspace:
         clean: all
       steps: