Add muted class to author name in repo commit list (#29989)

Before:

![image](f6b3728c-ed9a-4e47-8755-89373235dff2)

After:

![image](272c85e3-620d-4758-ae4d-ad90b54e142c)

If repo is a mirror, external user's name will be white, but if user is
existed, then you will see blue names and white names together:

![image](747622da-56e3-4162-b391-919787a8cee4)

---------

Co-authored-by: silverwind <me@silverwind.io>
(cherry picked from commit 13921569dd5f77ee7d8352d0036ff649b03e72c8)

web_src/css/repo.css

@@ -2432,6 +2432,7 @@ tbody.commit-list {
 
 .author-wrapper {
   max-width: 180px;
+  align-self: center;
 }
 
 /* in the commit list, messages can wrap so we can use inline */