[buster] Don't have a copy of linux-cip-ci's LAVA functions

!10 (merged) added lava.sh to check LAVA test results, but the functions in the script are copied from https://gitlab.com/cip-project/cip-testing/linux-cip-ci/-/blob/master/submit_tests.sh

Consider how these kind of functions to communicate with LAVA should be shared among multiple CIP projects.