Alerting: Allow provenance disable in alerting provisioning API (#63650)

* Allow provenance None in alert rule update and rule group replace

* Allow provenance None in contact point update

* Allow updating policies to none by sending x-disable-provenance header

* Allow mute timings to disable provenance with x-disable-provenance header

* Allow disabling provenance by using x-disable-provenance header

* Add provenance helper to lower the cyclomatic complexity

* Do not downgrade provenance except un ReplaceRuleGroup

* Add function explanation and change error handling

* Add docs for x-disable-provenance changes (#66300)

* Add docs for x-disable-provenance changes

* Apply suggestions from code review

Co-authored-by: brendamuir <100768211+brendamuir@users.noreply.github.com>

* Update _index.md

---------

Co-authored-by: brendamuir <100768211+brendamuir@users.noreply.github.com>

* Update docs/sources/alerting/set-up/provision-alerting-resources/_index.md

Co-authored-by: George Robinson <george.robinson@grafana.com>

* Add error message check in tests

* Change docs

---------

Co-authored-by: brendamuir <100768211+brendamuir@users.noreply.github.com>
Co-authored-by: George Robinson <george.robinson@grafana.com>

pkg/services/ngalert/provisioning/alert_rules_test.go

@@ -274,10 +274,10 @@ func TestAlertRuleService(t *testing.T) {
 				errNil: false,
 			},
 			{
-				name:   "should not be able to update from provenance api to none",
+				name:   "should be able to update from provenance api to none",
 				from:   models.ProvenanceAPI,
 				to:     models.ProvenanceNone,
-				errNil: false,
+				errNil: true,
 			},
 			{
 				name:   "should not be able to update from provenance file to api",