Drop support for obsolete environment variables

The RUNTIME was dropped from these names, but since we will no longer
be supporting them, they have been removed from the code.  There are
no active EFS environments where the use of these variables was ever
significant.
Require complete dependency specs for automated runtime expansion

For stability, when expanding the dependencies automatically when
running executables from /efs/dist, only the complete specification of
MPRs will be used.  The dynamic, heirarchical expansion will only be
supported whenusing environment variables (which are intended to be a
development and debugging aid, more than anything), or during the
build process as part of efsdeploy, when generating the actual
complete spec.