Feature / user recommendation config in admin ui (#3357)

* add config for external user recommendation into admin ui

* debug

* correct admin ui

* switch external user recommendation to admin ui config

* debug

* debug

* debug

* Revert "debug"

This reverts commit f4a0460e5bde21cd1f39a735f496a2d74233ef3f.

* explicit parseInt radix

* add Japanese message

* change default engine to https

* remove unused settings

* debug

* nullable externalUserRecommendationTimeout