chore: per template opt into cached terraform directories (#20609)

For experimental and dogfood purposes, this adds the ability to opt in a single template. 
Leaving the rest of the templates as is. 

For GA, this setting might be removed or changed.

coderd/database/queries/templates.sql

@@ -173,7 +173,8 @@ SET
 	group_acl = $8,
 	max_port_sharing_level = $9,
 	use_classic_parameter_flow = $10,
-	cors_behavior = $11
+	cors_behavior = $11,
+	use_terraform_workspace_cache = $12
 WHERE
 	id = $1
 ;