Replace metrics link to point to main

https://goo.gl/yNpRDV points to master.

Bug: 1314133
Change-Id: I14628f0a8cfa1cbd00e9287939b19f25b8c21621
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4409720
Commit-Queue: Aravind Vasudevan <aravindvasudev@google.com>
Auto-Submit: Gavin Mak <gavinmak@google.com>
Reviewed-by: Aravind Vasudevan <aravindvasudev@google.com>

metrics_utils.py

@@ -49,7 +49,7 @@ def get_notice_footer():
   yield '$ gclient metrics [--opt-in] [--opt-out]'
   yield 'For more information please see metrics.README.md'
   yield 'in your depot_tools checkout or visit'
-  yield 'https://goo.gl/yNpRDV.'
+  yield 'https://bit.ly/3MpLAYM.'
 
 def get_change_notice(version):
   if version == 0: