Add part of nightly-bench in CI
- Allows to run part of nightly-bench in gitlab:
- adds the possibility in prover upgrade policy to remove a prover
- adds the possibility in regtests to only run on a subset.
REGTESTS_MODE = REDUCEDmakes regtests reads in each directory
reduced_regtests.listfor the list of files to replay.
- install CVC4 1.4 1.5 and Z3 in the docker files
- use alt-ergo 2.0.0 instead of alt-ergo 2.2.0