ngalert openapi: Use same basePath as rest of Grafana (#79025)

* ngalert openapi: Use same `basePath` as rest of Grafana
Currently, there are two issues that prevent easily merging `ngalert` and grafana openapi specs:
- The basePath is different. `grafana` has `/api` and `ngalert` has `/api/v1`. I changed `ngalert` to use `/api`
- The `ngalert` endpoints have their basePath in the each operation path. The basePath should actually be omitted
---------

Co-authored-by: Yuriy Tseretyan <yuriy.tseretyan@grafana.com>

pkg/services/ngalert/api/tooling/definitions/testing.go

@@ -13,7 +13,7 @@ import (
 	"github.com/prometheus/prometheus/promql"
 )
 
-// swagger:route Post /api/v1/rule/test/grafana testing RouteTestRuleGrafanaConfig
+// swagger:route Post /v1/rule/test/grafana testing RouteTestRuleGrafanaConfig
 //
 // Test a rule against Grafana ruler
 //
@@ -28,7 +28,7 @@ import (
 //       400: ValidationError
 //       404: NotFound
 
-// swagger:route Post /api/v1/rule/test/{DatasourceUID} testing RouteTestRuleConfig
+// swagger:route Post /v1/rule/test/{DatasourceUID} testing RouteTestRuleConfig
 //
 // Test a rule against external data source ruler
 //
@@ -42,7 +42,7 @@ import (
 //       200: TestRuleResponse
 //       404: NotFound
 
-// swagger:route Post /api/v1/eval testing RouteEvalQueries
+// swagger:route Post /v1/eval testing RouteEvalQueries
 //
 // Test rule
 //
@@ -55,7 +55,7 @@ import (
 //     Responses:
 //       200: EvalQueriesResponse
 
-// swagger:route Post /api/v1/rule/backtest testing BacktestConfig
+// swagger:route Post /v1/rule/backtest testing BacktestConfig
 //
 // Test rule
 //