refactor #8661 - compute resource form partials

removing pointless try methods (try is send for everything except nil, for which it returns nil, so there's no point in something like foo && foo.try(:bar)
renaming the "new" variable to "new_host" to remove possible name confusion, as new can be used as a method call to the Class#new method if the current self is a class (not relevant here, but using reserved names for variable names is very bad for the next developer's mental health :smile: