Improve comment header for Mobile (#20781)

- Since
b9e8fa5beb
the avatar will be inlined into the comment header, so there's more room
for the actual comment container(thus more text per line in the comment
body). However this didn't take into consideration that the flex didn't
allow any wrapping and thus was shrinking the avatar. Well this isn't a
perfect solution, as you ideally all want these elements to be
individually wrapped(such that `comment-header-right` can be on the same
line as `comment-header-left`, which now causes a new line in certain
situations). It's a better solution than the current CSS and to not
mess with the desktop CSS/HTML.

Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: zeripath <art27@cantab.net>

web_src/less/_repository.less

@@ -3401,6 +3401,18 @@ td.blob-excerpt {
       }
     }
   }
+
+  .comment-header {
+    flex-wrap: wrap;
+
+    .comment-header-left {
+      flex-wrap: wrap;
+    }
+
+    .comment-header-right {
+      margin-left: auto;
+    }
+  }
 }
 
 .branch-dropdown-button {