Fix StartupChangeDisplayed on tabs !== Files

StartupChangeDisplayed should wait on FileList only when File tabs
is selected. When ?tab=checks we don't need to wait for file list,
it's not loading because it's hidden.

This caused wrong p99 values, because it was waiting for users to
click on file tab.

Release-Notes: skip
Google-Bug-Id: b/280828064
Change-Id: If6dc770bf3fbb68dbe8dedee1b369490282bc70a
(cherry picked from commit bfce9b023e93c27c5e711306ace306bc1dbf8315)
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
index 0bee919..abd3ff0 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
@@ -2275,8 +2275,10 @@
   private async reportChangeDisplayed() {
     await waitUntil(() => !!this.metadata);
     await untilRendered(this.metadata!);
-    await waitUntil(() => !!this.fileList);
-    await untilRendered(this.fileList!);
+    if (this.activeTab === Tab.FILES) {
+      await waitUntil(() => !!this.fileList);
+      await untilRendered(this.fileList!);
+    }
     await waitUntil(() => !!this.messagesList);
     await untilRendered(this.messagesList!);
     // We are ending the timer after each change view update, because ending a
@@ -2289,8 +2291,10 @@
   private async reportFullyLoaded() {
     await waitUntil(() => !!this.metadata);
     await untilRendered(this.metadata!);
-    await waitUntil(() => !!this.fileList);
-    await untilRendered(this.fileList!);
+    if (this.activeTab === Tab.FILES) {
+      await waitUntil(() => !!this.fileList);
+      await untilRendered(this.fileList!);
+    }
     await waitUntil(() => !!this.messagesList);
     await untilRendered(this.messagesList!);
     await waitUntil(() => this.mergeable !== undefined);