Fix id validation for custom service and SLO to match what's actually usable (#8939) (#15841)

* Fix slo_id pattern in google_monitoring_slo

* Fix servie_id pattern in google_monitoring_custom_service

Signed-off-by: Modular Magician <[email protected]>

Author: modular-magician

.changelog/8939.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+monitoring: fixed validation of `service_id` on `google_monitoring_custom_service` and `slo_id` on `google_monitoring_slo` 
+```

google/services/monitoring/resource_monitoring_custom_service.go

@@ -59,7 +59,7 @@ func ResourceMonitoringService() *schema.Resource {
 				Computed:     true,
 				Optional:     true,
 				ForceNew:     true,
-				ValidateFunc: verify.ValidateRegexp(`^[a-z0-9\-]+$`),
+				ValidateFunc: verify.ValidateRegexp(`^[a-zA-Z0-9\-_:.]+$`),
 				Description: `An optional service ID to use. If not given, the server will generate a
 service ID.`,
 			},

google/services/monitoring/resource_monitoring_slo.go

@@ -715,7 +715,7 @@ integer fraction of a day and at least 60s.`,
 				Computed:     true,
 				Optional:     true,
 				ForceNew:     true,
-				ValidateFunc: verify.ValidateRegexp(`^[a-z0-9\-]+$`),
+				ValidateFunc: verify.ValidateRegexp(`^[a-zA-Z0-9\-_:.]+$`),
 				Description:  `The id to use for this ServiceLevelObjective. If omitted, an id will be generated instead.`,
 			},
 			"user_labels": {