Don't re-exec in check-dg-tempest-dsvm-full

This job is intended to exercise the new code from the beginning
without re-execing, however, it was re-execing.  Set "RE_EXEC=true"
which tells d-g that the re-exec has already happened to ensure that
it does not run.

Change-Id: I7694f337c84b45afda73038898f58e9218e8b7dc
Merge "Don't re-exec in check-dg-tempest-dsvm-full"