revert/cherry-pick: do not mention the original ref

revert/cherry-pick: do not mention the original ref

When you cherry-pick or revert a commit, naming it with an annotated
tag, we added a comment, attempting to repeat what we got from the end
user, to the message.

But this was inconsistent.  When we got "cherry-pick branch", we
recorded the object name (40-letter SHA-1) without saying anything like
"original was 'branch'".  There was no need to.  Also recent rewrite to
use parse-options made it impossible to parrot the original command line
without "unparsing".

This removes the code that implements the misguided "we dereferenced the
tag so record that in the commit message" behaviour.

Signed-off-by: Junio C Hamano <gitster@pobox.com>