tests: Check job ordering on execution cycles

tests: Check job ordering on execution cycles

The test-engine Test2 tests the cycle detection when units a, b and d
all start at once

    ,-------------------after-----------------,
    v                                         |
    a/start ---after---> d/start ---after---> b/start

Extend the test with Test11 that adds i.service which causes a and d
stop (by unordered Conflicts=) while starting b. Because stops precede
starts, we effectively eliminate the job cycle and all transaction jobs
should be applicable.

    ,-------------------after-----------------,
    v                                         |
    a/stop <---after--- d/stop <---after--- b/start
    .                   .                     ^
    .                   .                     |
     '. . . . . . . . . i/start ---after------'