Cleanup iptables rules for other CNI networks

[lgfa29]

Proposal

#15407 introduced a mechanism to monitor and clean-up iptables rules created by Nomad. The code uses a regular expression to find rules managed by Nomad, but it hardcodes "name: \\"nomad\\" where nomad is the default name that Nomad uses for its built-in bridge. Users that have custom CNI bridges will have different names that would not match this expression and therefore may leak.

Use-cases

Run a custom bridge using CNI plugins.

Attempted Solutions

N/A

Note
Issue extracted from #13824. Refer to that issue for more context.