lisa.trace: Remove cpumask sanitization

BREAKING CHANGE

cpumask fields cannot be handled in a uniform way between all parsers,
so remove any attempts at doing so.  Since the new default trace-dump
parser has direct support for them, drop the sanitization.

The new format for cpumask values is an iterable of booleans where each
position corresponds to one bit, starting from CPU 0, e.g. [True, False,
False] for the cpumask 0b100