fix(observability): remove invalid fields match and match_regex from main route in alert_config (#915)

* fix: remove invalid `match` and `match_regex` from main route in alert_config
- deprecated `match` and `match_regex` in child routes
- add new `matchers` field

stackit/internal/services/observability/testdata/resource-max.tf

@@ -42,6 +42,7 @@ variable "smtp_from" {}
 variable "smtp_smart_host" {}
 variable "match" {}
 variable "match_regex" {}
+variable "matchers" {}
 
 variable "logalertgroup_name" {}
 variable "logalertgroup_alert" {}
@@ -151,6 +152,9 @@ resource "stackit_observability_instance" "instance" {
           match_regex = {
             match_regex1 = var.match_regex
           }
+          matchers = [
+            var.matchers
+          ]
         }
       ]
     },