Test started failing after
https://github.com/paritytech/polkadot-sdk/commit/66051adb


which enabled approval coalescing, that was expected to happen because
the test required an polkadot_parachain_approval_checking_finality_lag
of 0, which can't happen with max_approval_coalesce_count greater than 1
because we always delay the approval for no_show_duration_ticks/2 in
case we can coalesce it with other approvals.


So relax a bit the restrictions, since we don't actually care that the
lags are 0, but the fact the finalities are progressing and are not
stuck.

Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>