Fixes undeleted SQL queries in IsBanned() (#77105)

Discovered while working on #76663

## About The Pull Request

We were getting undeleted SQL stack traces with the following:
`[2023-07-25 19:27:33.832] DEBUG-SQL: Undeleted query: "SELECT 1 FROM
player WHERE ckey = :ckey" LA: NextRow LAT: 39397`

There's only one spot in the code (which happens to be the newest,
introduced in #74496 / 8fc56cbda0) where
we don't always qdel the query regardless of the path the proc takes
(and that seems to match the error per the `LA` field), so let's make
sure we always clean that up since it's a drather silly runtime. It's
also rather spontaneous, as this code is only executed when servers are
bunkered up (which Sybil presently is)

This is my first time dealing with SQL Query code, so let me know if I'm
missing something critical here.

code/modules/admin/IsBanned.dm

@@ -43,13 +43,15 @@
 
 		var/client_is_in_db = query_client_in_db.NextRow()
 		if(!client_is_in_db)
-			
 			var/reject_message = "Failed Login: [ckey] [address]-[computer_id] - New Account attempting to connect during panic bunker, but was rejected due to no prior connections to game servers (no database entry)"
 			log_access(reject_message)
 			if (message)
 				message_admins(span_adminnotice("[reject_message]"))
+			qdel(query_client_in_db)
 			return list("reason"="panicbunker", "desc" = "Sorry but the server is currently not accepting connections from never before seen players")
 
+		qdel(query_client_in_db)
+
 	//Whitelist
 	if(!real_bans_only && !C && CONFIG_GET(flag/usewhitelist))
 		if(!check_whitelist(ckey))