lisa.tests.base: Remove FtraceTestBundleMeta
lisa.tests.base: Remove FtraceTestBundleMeta

Remove the metaclass and replace it by implementing __init_subclass__.
This simplifies a bit the codebase for newcomers.

ARM-software/lisa,ARM-software/lisa,credp/lisa,credp/lisa,credp/lisa,ARM-software/lisa,ARM-software/lisa,credp/lisa