Use return code in iptables --check to verify is rule exists (salt/modules/iptables.py)
Use return code in iptables --check to verify is rule exists (salt/modules/iptables.py)

Since the check option in iptables was introduced (https://git.netfilter.org/iptables/commit/?id=d59b9db031abee37a9aa9776662dd15370faabf4) it's safe to use the return code to check if a rule exists or not.
Before this commit salt would check if the return from `iptables --check` was empty, if it was it assumed the rule was there. Since Debian Bullseye `iptables --check` return the active rule breaking `iptables.checks` module.

This commit changes this to return True or False based on the `cmd.run` returncode.

Signed-off-by: Daan van Gorkum <8e0310c5e70d5b5a6eabbb3462f553d01bf8c0ba@djvg.net>
Fixes: 60467

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt