Different logic for selecting organization if user belongs to oph

Using the old logic instead, only the root is initially fetched and
search uses the method provided by organizations service
ResetSearch functionality into OrganizationTreeModel

Should provide better user experience, no need to initialize
organizations as often. Removed use of debounce since it wasn't
UI-friendly with current implementation. However, OPH functionality
might still require it.
Removed dead code

Variable oph wasn't used.
Separated logic for OPH organization functionality into separate model

Reduces if-else jungle considerably.
Changed global constant service name to uppercase
Separate common functionality from OrganizationTreeModels into new object
Remove REST call from initialization of OrganisaatioOPHTreeModel

It will be called anyway when resetSearch is called from watcher. Might
change it to something else in the future since it is a bit confusing
even though it is less code.
Making functionality of OrganizationTreeModels similar

Also removed the bug that caused nothing to be found because property
existed but was blanked for some reason.
Take childorganizations into account when calculating number of hits
Remove search for other languages besides finnish

Leaving it this way until localization is supported project-wise.
Search organizations by skipping parents for OPH