Visual update: Update feature flag for internal users (#6356)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/72649045549333/task/1210728138839415

### Description

This PR makes sure the internal users always see the new visual update
UI.

Author: 0nko

common/common-ui/src/main/java/com/duckduckgo/common/ui/experiments/visual/ExperimentalThemingFeature.kt

@@ -30,7 +30,8 @@ interface ExperimentalThemingFeature {
     @Toggle.DefaultValue(DefaultFeatureValue.FALSE)
     fun self(): Toggle
 
-    @Toggle.DefaultValue(DefaultFeatureValue.INTERNAL)
+    @Toggle.InternalAlwaysEnabled
+    @Toggle.DefaultValue(DefaultFeatureValue.FALSE)
     fun singleOmnibarFeature(): Toggle
 
     enum class ExperimentalThemingCohortName(override val cohortName: String) : CohortName {