revert: using string replacement for whitespace checking

Ref: bc08c149b7.

mastodon/src/main/java/org/joinmastodon/android/ui/displayitems/StatusDisplayItem.java

@@ -280,9 +280,6 @@ public abstract class StatusDisplayItem{
 					Matcher matcher=QUOTE_MENTION_PATTERN.matcher(status.content);
 					if(matcher.find()){
 						String quoteMention=matcher.group();
-						// FIXME: This is ugly. I wanna do it all in the regex >:(
-						if(statusForContent.content.contains("RE:<br />"+quoteMention))
-							quoteMention = "RE:<br />"+quoteMention;
 						statusForContent.content=statusForContent.content.replace(quoteMention, "");
 					}
 				}