Use bump events for broadcasting anchor commitment txn even if they have enough fees

[TheBlueMatt]

We currently have an optimization to bypass the anchor commitment bump events if the commitment tx has enough fees on its own. This is great, except some users don't want to broadcast anchor commitment txn at all if they trust an LSP and don't want to have reserves. For them, this optimization makes it hard to avoid broadcasting (which would result in HTLCs being un-claimable against their commitment transaction), so we should probably drop it.

[wpaulino]

Rather than dropping the optimization, we should move it to the BumpTransactionEventHandler instead so users still benefit.