Forbid 4.4 mongod binaries from starting up on 4.0 data files

The WT version to be released with 4.4 is not capable of emitting checkpoints that a 4.0 binary will understand. If WT fails to start up on 4.2 datafiles (WT version 3.1.0), MongoDB should not fall back to trying on 4.0/3.6 data files (WT version 3.0.0).

Care should be taken to leave repair code intact when WT returns a "try salvage" error code.