Moving app from singular to being created for every request (#9889)

* Moving app from singular to being created for every request.

* Automatic refactor

* Adding license header

* Feedback fixes

utils/testutils/static_config_service.go

@@ -4,6 +4,8 @@
 package testutils
 
 import (
+	"crypto/ecdsa"
+
 	"github.com/mattermost/mattermost-server/model"
 )
 
@@ -22,3 +24,7 @@ func (StaticConfigService) AddConfigListener(func(old, current *model.Config)) s
 func (StaticConfigService) RemoveConfigListener(string) {
 
 }
+
+func (StaticConfigService) AsymmetricSigningKey() *ecdsa.PrivateKey {
+	return &ecdsa.PrivateKey{}
+}