itest: fix issues caused by the bump to lnd 0.15.4-beta

In https://github.com/lightninglabs/faraday/pull/152, the lnd version that faraday uses was bumped from v0.15.-0-beta to v0.15.4-beta. This then caused some of the faraday itests to break. Specifically:

1. The `closeChannel` method started to use a zero value fee. This has temporarily been solved by ignoring the used fee and instead using a hardcoded fee value. See [1](https://github.com/lightninglabs/faraday/blob/master/itest/nodereport_test.go#L62) and [2](https://github.com/lightninglabs/faraday/blob/master/itest/nodereport_test.go#L173)
2. The [second issue](https://github.com/lightninglabs/faraday/blob/master/accounting/filter.go#L49) is that force closes no longer show up as confirmed in the itest. This could possibly due to the first issue? Perhaps the zero fee txs dont get accepted into the mempool?

Start with the itest cases in itest/nodereport_test.go, especially the references around lines 62 and 173, and inspect accounting/filter.go around line 49. Run the affected integration tests against the lnd v0.15.4-beta dependency and compare the close-channel fee and force-close confirmation behavior. Done means the itests pass without relying on the temporary hardcoded fee workaround.

Written by the indexing model from the issue text.