[REF] reqgen: Search requirements files based on parameter

In order to be able to looking for requirements-test.txt where it is needed
4 jobs for req-test-moy in 42 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #1002330
lint
lint

00:00:37

passed #1002331
test python
testpy27

00:00:40

passed #1002332
test python
testpy34

00:00:41

passed #1002333
test python
testpy35

00:00:41