Add more unit tests for removeSSOSettings method (#78329)

* add more unit tests for remove sso settings

* add unit tests for the service method

pkg/services/ssosettings/api/api.go

@@ -1,6 +1,7 @@
 package api
 
 import (
+	"errors"
 	"net/http"
 
 	"github.com/grafana/grafana/pkg/api/response"
@@ -121,6 +122,9 @@ func (api *Api) removeProviderSettings(c *contextmodel.ReqContext) response.Resp
 
 	err := api.SSOSettingsService.Delete(c.Req.Context(), key)
 	if err != nil {
+		if errors.Is(err, ssosettings.ErrNotFound) {
+			return response.Error(http.StatusNotFound, "The provider was not found", err)
+		}
 		return response.Error(http.StatusInternalServerError, "Failed to delete provider settings", err)
 	}