CI: Trigger *-storybook steps on UI changes (#54833)

* No-op, small starlark refactoring

* Make build and store storybook steps execute on ui changes

scripts/drone/steps/lib.star

@@ -11,10 +11,15 @@ wix_image = 'grafana/ci-wix:0.1.1'
 
 disable_tests = False
 trigger_oss = {
-    'when': {
-        'repo': [
-            'grafana/grafana',
-        ]
+    'repo': [
+        'grafana/grafana',
+    ]
+}
+trigger_storybook = {
+    'paths': {
+        'include': [
+            'packages/grafana-ui/**',
+        ],
     }
 }
 
@@ -249,6 +254,7 @@ def build_storybook_step(edition, ver_mode):
             'yarn storybook:build',
             './bin/grabpl verify-storybook',
         ],
+        'when': trigger_storybook,
     }
 
 
@@ -276,9 +282,19 @@ def store_storybook_step(edition, ver_mode, trigger=None):
             'PRERELEASE_BUCKET': from_secret(prerelease_bucket)
         },
         'commands': commands,
+        'when': trigger_storybook,
     }
     if trigger and ver_mode in ("release-branch", "main"):
-        step.update(trigger)
+        # no dict merge operation available, https://github.com/harness/drone-cli/pull/220
+        when_cond = {
+            'repo': ['grafana/grafana',],
+            'paths': {
+                'include': [
+                    'packages/grafana-ui/**',
+                ],
+            }
+        }
+        step = dict(step, when=when_cond)
     return step
 
 
@@ -345,7 +361,7 @@ def upload_cdn_step(edition, ver_mode, trigger=None):
         ],
     }
     if trigger and ver_mode in ("release-branch", "main"):
-        step.update(trigger)
+        step = dict(step, when=trigger)
     return step
 
 
@@ -596,7 +612,7 @@ def frontend_metrics_step(edition, trigger=None):
         ],
     }
     if trigger:
-        step.update(trigger)
+        step = dict(step, when=trigger)
     return step
 
 
@@ -824,7 +840,7 @@ def publish_images_step(edition, ver_mode, mode, docker_repo, trigger=None):
         }],
     }
     if trigger and ver_mode in ("release-branch", "main"):
-        step.update(trigger)
+        step = dict(step, when=trigger)
 
     return step
 
@@ -921,7 +937,7 @@ def release_canary_npm_packages_step(edition, trigger=None):
         ],
     }
     if trigger:
-        step.update(trigger)
+        step = dict(step, when=trigger)
     return step
 
 
@@ -954,7 +970,7 @@ def upload_packages_step(edition, ver_mode, trigger=None):
         'commands': ['./bin/grabpl upload-packages --edition {}'.format(edition),],
     }
     if trigger and ver_mode in ("release-branch", "main"):
-        step.update(trigger)
+        step = dict(step, when=trigger)
     return step