util/unittests: delete PASS_IF macro

util/unittests: delete PASS_IF macro

The logic flow we want to achieve with unittests, where first we have
all FAIL statements and then just one PASS statement could become more
convoluted with the existence of the PASS_IF macro. Besides, what could
be written as a FAIL_IF might in some cases be written in not so clear
ways with the PASS_IF option available.

Also: fix inverted check values in documentation, update copyright year

Optimization: #4795