Backport #34412 by wxiaoguang
Fix#34398, fix#33308
Remove all `repo.ComposeCommentMetas` from templates,
only use `repo` to render commit message.
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
This PR removes (almost) all path tricks, and introduces "renderhelper"
package.
Now we can clearly see the rendering behaviors for comment/file/wiki,
more details are in "renderhelper" tests.
Fix#31411 , fix#18592, fix#25632 and maybe more problems. (ps: fix
#32608 by the way)
