Service accounts: Grafana service accounts are enabled by default (#51402)

* Remove feature flag for service accounts

* Fix failing tests and remove remaining usage

* Fix failing tests and remove remaining usage

pkg/api/index.go

@@ -151,9 +151,6 @@ func (hs *HTTPServer) getAppLinks(c *models.ReqContext) ([]*dtos.NavLink, error)
 }
 
 func enableServiceAccount(hs *HTTPServer, c *models.ReqContext) bool {
-	if !hs.Features.IsEnabled(featuremgmt.FlagServiceAccounts) {
-		return false
-	}
 	hasAccess := ac.HasAccess(hs.AccessControl, c)
 	return hasAccess(ac.ReqOrgAdmin, serviceAccountAccessEvaluator)
 }
@@ -298,7 +295,6 @@ func (hs *HTTPServer) getNavTree(c *models.ReqContext, hasEditPerm bool, prefs *
 			Url:         hs.Cfg.AppSubURL + "/org/apikeys",
 		})
 	}
-	// needs both feature flag and migration to be able to show service accounts
 	if enableServiceAccount(hs, c) {
 		configNodes = append(configNodes, &dtos.NavLink{
 			Text:        "Service accounts",