test: refactor: take use of create_block txlist parameter

Passing a list of transactions `txlist` to `create_block` appends
them to the block, hence we don't need to do that manually anymore.
The merkle root calculation can also be removed, since this is done
in the end of the helper.

test/functional/wallet_bumpfee.py

@@ -24,7 +24,6 @@ from test_framework.blocktools import (
 )
 from test_framework.messages import (
     BIP125_SEQUENCE_NUMBER,
-    tx_from_hex,
 )
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
@@ -588,13 +587,10 @@ def spend_one_input(node, dest_address, change_size=Decimal("0.00049000")):
 
 
 def submit_block_with_tx(node, tx):
-    ctx = tx_from_hex(tx)
     tip = node.getbestblockhash()
     height = node.getblockcount() + 1
     block_time = node.getblockheader(tip)["mediantime"] + 1
-    block = create_block(int(tip, 16), create_coinbase(height), block_time)
-    block.vtx.append(ctx)
-    block.hashMerkleRoot = block.calc_merkle_root()
+    block = create_block(int(tip, 16), create_coinbase(height), block_time, txlist=[tx])
     add_witness_commitment(block)
     block.solve()
     node.submitblock(block.serialize().hex())