Locale: say another issue instead of this issue (#14082)

Saying "this issue" is confusing because it could be understood as the
issue that the user is currently viewing, not which the "issue" link
points to.

options/locale/locale_en-US.ini

@@ -1131,7 +1131,7 @@ issues.start_tracking_short = Start
 issues.start_tracking = Start Time Tracking
 issues.start_tracking_history = `started working %s`
 issues.tracker_auto_close = Timer will be stopped automatically when this issue gets closed
-issues.tracking_already_started = `You have already started time tracking on this <a href="%s">issue</a>!`
+issues.tracking_already_started = `You have already started time tracking on <a href="%s">another issue</a>!`
 issues.stop_tracking = Stop
 issues.stop_tracking_history = `stopped working %s`
 issues.add_time = Manually Add Time