add tests with ES and CS 10.5 - 10.7 backend to BB

regular testing with both ES and CS backend is needed:

2.5, 6 with ES 10.5, 10.6, CS 10.5 - 10.7
2.4 with ES 10.6, CS 10.6

on push tests - consider "one out of 10 commits" is tested with all backends