fix: DeleteStale from relational tables as well (#5143)

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#### Summary
Won't compile until cloudquery/plugin-sdk#443 is
merged.


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Co-authored-by: Yevgeny Pats <yev.pats@gmail.com>

plugins/destination/postgresql/client/deletestale.go

@@ -12,7 +12,7 @@ import (
 
 func (c *Client) DeleteStale(ctx context.Context, tables schema.Tables, source string, syncTime time.Time) error {
 	batch := &pgx.Batch{}
-	for _, table := range tables {
+	for _, table := range tables.FlattenTables() {
 		var sb strings.Builder
 		sb.WriteString("delete from ")
 		sb.WriteString(pgx.Identifier{table.Name}.Sanitize())

plugins/destination/snowflake/client/deletestale.go

@@ -9,7 +9,7 @@ import (
 )
 
 func (c *Client) DeleteStale(ctx context.Context, tables schema.Tables, source string, syncTime time.Time) error {
-	for _, table := range tables {
+	for _, table := range tables.FlattenTables() {
 		var sb strings.Builder
 		sb.WriteString("delete from ")
 		sb.WriteString(table.Name)

plugins/destination/sqlite/client/deletestale.go

@@ -9,7 +9,7 @@ import (
 )
 
 func (c *Client) DeleteStale(ctx context.Context, tables schema.Tables, source string, syncTime time.Time) error {
-	for _, table := range tables {
+	for _, table := range tables.FlattenTables() {
 		var sb strings.Builder
 		sb.WriteString("delete from ")
 		sb.WriteString(`"` + table.Name + `"`)