It means: a) user cannot be created, something's wrong in the
test environment -> fail the test; b) user already exists, we shall not
continue and delete (foreign) user.
When the test used to be run on distro that doesn't enable memory
accounting by default (such as openSUSE TW), there is no guarantee that
testing unit has memory.* cgroup attributes and delegation test would
fail if they are missing.
Require memory controller explicitly inside the unit so that test can
work in any environment.
Having these named differently than the test itself mostly creates
unecessary confusion and makes writing logic against the tests harder
so let's rename the testsuite-xx units and scripts to just use the
test name itself.