Provisioning: Make image renderer note optional in PR comments (#113837)

* Provisioning: Remove image renderer note from PR comment template

Removes the 'NOTE: The image renderer is not configured' message from
the pull request comment template when image renderer is unavailable.
This addresses issue #656 in git-ui-sync-project.

- Updated commentTemplateMissingImageRenderer to be empty
- Updated testdata to reflect the change
- All unit tests pass

* Provisioning: Make image renderer note optional in PR comments

Make the image renderer note in pull request comments optional based on
the allowImageRendering configuration flag. When enabled, the note now
includes a link to the setup documentation.

- Add showImageRendererNote boolean field to commenter struct
- Update NewCommenter to accept showImageRendererNote parameter
- Update template to conditionally show note with documentation link
- Pass allowImageRendering from APIBuilder to commenter in register.go
- Update ProvidePullRequestWorker to use cfg.ProvisioningAllowImageRendering
- Add tests to verify note appears/disappears based on flag

Fixes https://github.com/grafana/git-ui-sync-project/issues/656

* Format code with go fmt

* Remove redundant text from image renderer note

Remove 'The image renderer is not configured.' from the note message.
The note now focuses on actionable guidance with the documentation link.

* Fix compilation error: use cfg.ProvisioningAllowImageRendering directly

Cannot access unexported field allowImageRendering from webhooks package.
Use cfg.ProvisioningAllowImageRendering directly since we have access to cfg.

pkg/registry/apis/provisioning/webhooks/pullrequest/comment_test.go

@@ -21,7 +21,7 @@ func TestCommenter_Comment_FailedToComment(t *testing.T) {
 	repo := NewMockPullRequestRepo(t)
 	repo.On("CommentPullRequest", context.Background(), 1, mock.Anything).Return(errors.New("failed"))
 
-	commenter := NewCommenter()
+	commenter := NewCommenter(false)
 	err := commenter.Comment(context.Background(), repo, 1, changeInfo{})
 	require.Error(t, err)
 }
@@ -138,9 +138,78 @@ func TestGenerateComment(t *testing.T) {
 			require.NoError(t, err)
 			repo.On("CommentPullRequest", context.Background(), 1, string(expect)).Return(nil)
 
-			commenter := NewCommenter()
+			commenter := NewCommenter(false)
 			err = commenter.Comment(context.Background(), repo, 1, tc.Input)
 			require.NoError(t, err)
 		})
 	}
 }
+
+func TestCommenter_ShowImageRendererNote(t *testing.T) {
+	t.Run("note appears when showImageRendererNote is true", func(t *testing.T) {
+		repo := NewMockPullRequestRepo(t)
+		info := changeInfo{
+			GrafanaBaseURL: "http://host/",
+			Changes: []fileChangeInfo{
+				{
+					Parsed: &resources.ParsedResource{
+						Info: &repository.FileInfo{
+							Path: "file.json",
+						},
+						Action: v0alpha1.ResourceActionUpdate,
+						GVK:    schema.GroupVersionKind{Kind: "Dashboard"},
+					},
+					Title:      "Existing Dashboard",
+					GrafanaURL: "http://grafana/d/uid",
+					PreviewURL: "http://grafana/admin/preview",
+				},
+			},
+			MissingImageRenderer: true,
+		}
+
+		var capturedComment string
+		repo.On("CommentPullRequest", context.Background(), 1, mock.MatchedBy(func(comment string) bool {
+			capturedComment = comment
+			return true
+		})).Return(nil)
+
+		commenter := NewCommenter(true)
+		err := commenter.Comment(context.Background(), repo, 1, info)
+		require.NoError(t, err)
+		require.Contains(t, capturedComment, "NOTE: To enable dashboard previews")
+		require.Contains(t, capturedComment, "https://grafana.com/docs/grafana/latest/observability-as-code/provision-resources/git-sync-setup/#configure-webhooks-and-image-rendering")
+	})
+
+	t.Run("note does not appear when showImageRendererNote is false", func(t *testing.T) {
+		repo := NewMockPullRequestRepo(t)
+		info := changeInfo{
+			GrafanaBaseURL: "http://host/",
+			Changes: []fileChangeInfo{
+				{
+					Parsed: &resources.ParsedResource{
+						Info: &repository.FileInfo{
+							Path: "file.json",
+						},
+						Action: v0alpha1.ResourceActionUpdate,
+						GVK:    schema.GroupVersionKind{Kind: "Dashboard"},
+					},
+					Title:      "Existing Dashboard",
+					GrafanaURL: "http://grafana/d/uid",
+					PreviewURL: "http://grafana/admin/preview",
+				},
+			},
+			MissingImageRenderer: true,
+		}
+
+		var capturedComment string
+		repo.On("CommentPullRequest", context.Background(), 1, mock.MatchedBy(func(comment string) bool {
+			capturedComment = comment
+			return true
+		})).Return(nil)
+
+		commenter := NewCommenter(false)
+		err := commenter.Comment(context.Background(), repo, 1, info)
+		require.NoError(t, err)
+		require.NotContains(t, capturedComment, "NOTE: To enable dashboard previews")
+	})
+}