lnwatcher: remove rearly return that breaks accounting_addresses

This reverts 6ffaa55.
Also, in regtests, add a check that fails if accounting_addresses are broken.

tests/regtest/regtest.sh

@@ -344,6 +344,12 @@ if [[ $1 == "swapserver_forceclose" ]]; then
     wait_until_spent $ctx_id $output_index
     new_blocks 144
     wait_for_balance bob 0.999
+    # check that the closing tx is in alice's onchain_history. Since this tx does not
+    # touch alice's wallet addresses, this test requires accounting_addresses to be set
+    if [[ ! $($alice onchain_history| jq --arg txid $ctx_id '.[]|select(.txid == $txid)') ]]; then
+       echo "accounting_address not set"
+       exit 1
+    fi
 fi