Change bug prefix to point to issue tracker

Bug: b/293322202
Change-Id: I5147962b9d8e590bbdecf9c4b720f43463bff45e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/730079
Commit-Queue: Ravi Mistry <[email protected]>
Reviewed-by: Leandro Lovisolo <[email protected]>

Author: rmistry

codereview.settings

@@ -2,7 +2,7 @@
 CODE_REVIEW_SERVER: codereview.chromium.org
 VIEW_VC: https://skia.googlesource.com/skia/+/
 CC_LIST: [email protected]
-BUG_PREFIX: skia:
+BUG_PREFIX: b/
 TRYSERVER_SVN_URL: https://skia-try.googlecode.com/svn
 PROJECT: skia
 GERRIT_HOST: True