Based on manual inspection (that the command only does a submit of some
jobs/opcodes), we re-add the dry-run option on a subset of the existing
commands.

A few more commands could use dry-run, but the code doesn't deal nicely
with no results, so fixing those is left for later patches.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>