pg_stat_statements: Remove obsolete comment

Since 4f0b096, pgss_store() does nothing if compute_query_id is disabled
or if no other module computed a query identifier, but the top comment
of this function did not reflect that.  This behavior is already
documented in its own code path, and this just removes the inconsistent
comment.

Author: Kyotaro Horiguchi
Reviewed-by: Julien Rouhaud
Discussion: https://postgr.es/m/20211122.153823.1325120762360533122.horikyota.ntt@gmail.com
Backpatch-through: 14

contrib/pg_stat_statements/pg_stat_statements.c

@@ -1191,10 +1191,6 @@ pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
 /*
  * Store some statistics for a statement.
  *
- * If queryId is 0 then this is a utility statement for which we couldn't
- * compute a queryId during parse analysis, and we should compute a suitable
- * queryId internally.
- *
  * If jstate is not NULL then we're trying to create an entry for which
  * we have no statistics as yet; we just want to record the normalized
  * query string.  total_time, rows, bufusage and walusage are ignored in this