Skip the 'download-dist' step for full integ-test

After the '[bot] update dist directory' commit, we run a full test suite.
This will now use the content from the 'dist' directory, rather than
regenerating this content in the test.

.github/workflows/integ-test-restore-custom-gradle-home.yml

@@ -5,8 +5,12 @@ on:
     inputs:
       cache-key-prefix:
         type: string
+      skip-dist:
+        type: boolean
+        default: false
 
 env:
+  SKIP_DIST: ${{ inputs.skip-dist }}
   GRADLE_BUILD_ACTION_CACHE_KEY_PREFIX: restore-custom-gradle-home-${{ inputs.cache-key-prefix }}
 
 jobs: