[fix] SQLAlchemy warning on subquery in IN clause

The follow warning message suggests that the IN clause should be given
the query instead of the subquery object:

codechecker_server/api/report_server.py:3554: SAWarning: Coercing Subquery object into a select() for use in IN(); please pass a select() construct explicitly

Author: bruntib

web/server/codechecker_server/api/report_server.py

@@ -3535,8 +3535,6 @@ def getRunHistoryTagCounts(self, run_ids, report_filter, cmp_data, limit,
                 tag_run_ids = tag_run_ids.filter(
                     RunHistory.run_id.in_(run_ids))
 
-            tag_run_ids = tag_run_ids.subquery()
-
             report_cnt_q = session.query(Report.run_id,
                                          Report.bug_id,
                                          Report.detected_at,