Remove localizationForPlugins feature toggle and make this a default behavior - targeting Grafana 12.2.0.

Cleanup:

• source code in grafana/grafana
• once the removal is merged and rolled out to all cloud waves, remove the feature toggle configs in https://github.com/search?q=org%3Agrafana+repo%3Agrafana%2Fdeployment_tools+localizationForPlugins&type=code