Revert "commit-msg: Insert Change-Id at start of trailers"
Revert "commit-msg: Insert Change-Id at start of trailers"

This reverts commit 653f8b711be3344e8c617512629270661b24fa86.

Reason for revert: This requires git-2.15 which is much newer than
repo itself requires.  Lets pull it until we can figure out something
on the Gerrit side.

Bug: https://crbug.com/gerrit/12546
Change-Id: I5148f8a9cab5f0c305c020e31627b4af88cd5c95
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/263012
Reviewed-by: David Pursehouse <e7b5c6a4a3dbaca972851f8c075e19915752593f@collab.net>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@google.com>

couchbasedeps/git-repo,aosp-mirror/tools_repo,TheQtCompany/git-repo,mer-tools/git-repo,GerritCodeReview/git-repo,mer-tools/git-repo,lipro-yocto/git-repo,TheQtCompany/git-repo,lewixliu/git-repo,codetutil/git-repo,codetutil/git-repo,GerritCodeReview/git-repo,lewixliu/git-repo,lipro-yocto/git-repo,couchbasedeps/git-repo,aosp-mirror/tools_repo