Fix(zombienet): allow finality_lag be to be 1 or less and increase timeout (#3299)

Change `parityDb` test assertions after a quick check with @alexggh in
order to resolve failures in
`zombienet-polkadot-misc-0001-parachains-paritydb`(e.g
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/5186277).
Thx!