Revert "Only search Content, not Content and Subject, for better inde…

…xing"

This reverts commit 8450f0a.

As we support to separate fulltext search terms from others in 8788a99,
the performance penalty is gone for searches like

    Subject LIKE 'foo' OR Content LIKE 'foo'

Via searching both Subject and Content, now we can cover cases where
modified Subject is not included in any attachments.

lib/RT/Search/Simple.pm

@@ -280,7 +280,7 @@ sub GuessType {
 sub HandleDefault   {
     my $fts = RT->Config->Get('FullTextSearch');
     if ($fts->{Enable} and $fts->{Indexed}) {
-        return default => "Content LIKE '$_[1]'";
+        return default => "(Subject LIKE '$_[1]' OR Content LIKE '$_[1]')";
     } else {
         return default => "Subject LIKE '$_[1]'";
     }