Issue #12751: Direct contributors to Bugzilla for issue tracking

Author: csadilek

.github/ISSUE_TEMPLATE/---performance-issue.md

@@ -0,0 +1,6 @@
+blank_issues_enabled: false
+contact_links:
+  - name: We are now using Bugzilla for issue tracking!
+    url: https://bugzilla.mozilla.org/enter_bug.cgi?product=Fenix
+    about: Please file your ticket there, and select the corresponding component from the list. If the component is not in the list, select "General". In commit messages, please reference the ticket using "Bug 1234567 - " as prefix.  
+