Convert the locking unittests to repetition-test

Currently the locking tests are using timeouts to ensure an event will
'never happen'. However, this is suboptimal.

The patch converts all of these to instead: not wait, but sequence the
operations logically and expect that they execute as such. In case of
not so, they will timeout with a big (60s) timeout.

The 'never happen' is tested by multiple repetitions of the same test -
this is not perfect, but again 'X will never happen' is not actually
testable.

This patch reduces the runtime of the tests from ~5.4 to ~0.8 seconds
(with 8 repetitions of each test thas has 'never happen' situations).

Reviewed-by: imsnah