AuthN: Remove embedded oauth server (#83146)

* AuthN: Remove embedded oauth server

* Restore main

* go mod tidy

* Fix problem

* Remove permission intersection

* Fix test and lint

* Fix TestData test

* Revert to origin/main

* Update go.mod

* Update go.mod

* Update go.sum

pkg/services/authn/clients/basic.go

@@ -2,7 +2,6 @@ package clients
 
 import (
 	"context"
-	"strings"
 
 	"github.com/grafana/grafana/pkg/services/authn"
 	"github.com/grafana/grafana/pkg/util/errutil"
@@ -43,10 +42,6 @@ func (c *Basic) Test(ctx context.Context, r *authn.Request) bool {
 	if r.HTTPRequest == nil {
 		return false
 	}
-	// The OAuth2 introspection endpoint uses basic auth but is handled by the oauthserver package.
-	if strings.EqualFold(r.HTTPRequest.RequestURI, "/oauth2/introspect") {
-		return false
-	}
 	return looksLikeBasicAuthRequest(r)
 }