Alerting: Drop NamespaceID from responses on unstable ngalert API endpoints in favor of NamespaceUID (#79359)

* Drop from API response

* Drop from swagger docs

* Drop from integration tests

* regenerate public swagger docs

* Drop from frontend

* Drop asserts for namespaceID field

pkg/tests/api/alerting/test-data/rulegroup-1-get.json

@@ -38,7 +38,6 @@
         "version": 1,
         "uid": "<dynamic>",
         "namespace_uid": "<dynamic>",
-        "namespace_id": 0,
         "rule_group": "Group1",
         "no_data_state": "NoData",
         "exec_err_state": "Alerting",
@@ -81,7 +80,6 @@
         "version": 1,
         "uid": "<dynamic>",
         "namespace_uid": "<dynamic>",
-        "namespace_id": 0,
         "rule_group": "Group1",
         "no_data_state": "NoData",
         "exec_err_state": "Alerting",