tests/int/update: more cpu period/quota cases
tests/int/update: more cpu period/quota cases

Add four "corner case" tests that check that the CPU period/quota
can be set/updated even in case neither CPU quota nor CPU period
(were previously) set.

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

xiaochenshen/runc,xiaochenshen/runc,opencontainers/runc,dqminh/runc,xiaochenshen/runc,kolyshkin/runc,dqminh/runc,rhatdan/runc,dqminh/runc,opencontainers/runc,opencontainers/runc,opencontainers/runc,dqminh/runc,rhatdan/runc,kolyshkin/runc,estesp/runc,rhatdan/runc,mikebrow/runc,estesp/runc,estesp/runc,mikebrow/runc,mikebrow/runc,rhatdan/runc,kolyshkin/runc,kolyshkin/runc