Add --no-locks option to gnt-debug delay

Add the possibility to don't acquire locks during `gnt-debug delay`.
This allows to run many delay jobs in parallel instead of having
them run sequentially.

Signed-off-by: Thomas Thrainer <thomasth@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>