tests: don't test hostname if it looks like an id128

tests: don't test hostname if it looks like an id128

The condition tests for hostname will fail if hostname looks like an id128.
The test function attempts to convert hostname to an id128, and if that
succeeds compare it to the machine ID (presumably because the 'hostname'
condition test is overloaded to also test machine ID). That will typically
fail, and unfortunately the 'mock' utility generates a random hostname that
happens to have the same format as an id128, thus causing a test failure.