Change setTimeout interval to 100

a longer timeout interval causes tooltip to flash
"undefined" text.

See:
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/45035#note_430652834

app/assets/javascripts/behaviors/copy_to_clipboard.js

@@ -10,7 +10,7 @@ function showTooltip(target, title) {
     setTimeout(() => {
       target.setAttribute('title', originalTitle);
       fixTitle(target);
-    }, 300);
+    }, 100);
   };
 
   target.setAttribute('title', title);

changelogs/unreleased/268144-mr-widget-copy-branch-name-button-tooltip-occasionally-shows-undef.yml

+---
+title: Fix undefined tooltip text flashing on clipboard icon
+merge_request: 45482
+author:
+type: fixed