test/crimson/test_crimson_coroutine: introduce repeat example

test/crimson/test_crimson_coroutine: introduce repeat example

interruptible repeat methods use internally seastar::repeat which
require passing a seastar::stop_iteration.
Using coroutines, it's far nicer to use primitive for/while
loops with interrutible futures inside.

Adding interruptible_coroutine_interrupted_repeat as an example.
to a discussion from https://github.com/ceph/ceph/pull/65157

Signed-off-by: Matan Breizman <mbreizma@redhat.com>