undo part of PR 8202 to fix RTL (#8979)

app/javascript/styles/mastodon/stream_entries.scss

@@ -3,7 +3,6 @@
   border-radius: 4px;
   overflow: hidden;
   margin-bottom: 10px;
-  text-align: left;
 
   @media screen and (max-width: $no-gap-breakpoint) {
     margin-bottom: 0;