Improve permanentCheck jobs

Permanent checks

Permanent checks currently don't wait for nuxeo-features to be built but won't raise relevant issues until nuxeo-features is built.
In cases where there are a lot of commits, nuxeo-features build can take several hours.

=> need to change that

So basically, we could have permanent checks be closer to the IT builds :

rebuild everything from zero
do build / no UT / distrib on a fast slave
dispatch non-reg tests on different hosts