Tezt/LTF: long dynamic bake ring/clique: up and running bakers at start

The initial test needed around 37 seconds on my machine to have the 4 initial crashed baker replaced by running ones. The patched one has 4 baker up and running at the beginning of the test.

Hugely decrease the time needed to run tests:

Without the patch:

[08:56:52.634] Test terminated in 78.566628 seconds, expected max time: 44
[08:58:19.522] Test terminated in 78.685392 seconds, expected max time: 44
[08:59:46.382] Test terminated in 78.807466 seconds, expected max time: 44
[09:00:59.305] Test terminated in 68.870145 seconds, expected max time: 44
[09:02:35.216] Test terminated in 84.008676 seconds, expected max time: 44

With:

[08:52:00.107] Test terminated in 34.040153 seconds, expected max time: 44
[08:52:27.808] Test terminated in 23.315329 seconds, expected max time: 44
[08:52:55.527] Test terminated in 23.600271 seconds, expected max time: 44
[08:53:23.367] Test terminated in 23.755763 seconds, expected max time: 44
[08:54:01.037] Test terminated in 34.100651 seconds, expected max time: 44