s/Get(Master|Replica)X/Get\1/g (#29520)

Drop the legacy `X` suffix from `GetMasterX` and `GetReplicaX`. The
presence of the suffix suggests there's a `non-X` version: but in fact
we migrated these away a long time ago, so remove the cognitive
overhead.

As an aside, this additionally helps avoid trip up LLMs that interpret
this as "something to fix".

server/channels/store/sqlstore/context.go

@@ -48,7 +48,7 @@ func HasMaster(ctx context.Context) bool {
 // DBXFromContext is a helper utility that returns the sqlx DB handle from a given context.
 func (ss *SqlStore) DBXFromContext(ctx context.Context) *sqlxDBWrapper {
 	if HasMaster(ctx) {
-		return ss.GetMasterX()
+		return ss.GetMaster()
 	}
-	return ss.GetReplicaX()
+	return ss.GetReplica()
 }