Migrate Select and MultiSelect components to Combobox

[VikaCep]

After #1226, we started using grafana/ui v12 which deprecates Select components in favor of Combobox. We should replace its usage as currently the lint warning is being silenced.

MultiSelect should also be moved to Combobox as they were recently deprecated in 12.3.0.

See https://github.com/grafana/plugin-tools/blob/674424824e159fec79c7917b916b66e690a9062a/docusaurus/docs/migration-guides/update-from-grafana-versions/v11.6.x-v12.0.x.md?plain=1#L160