Merge bitcoin/bitcoin#33269: test: Fixup fill_mempool docstring

fa3f682 test: Fixup fill_mempool docstring (MarcoFalke)

Pull request description:

  The assumption was removed in commit
  3eab8b7.

ACKs for top commit:
  l0rinc:
    ACK fa3f682
  enirox001:
    ACK bitcoin/bitcoin@fa3f682 - docstring cleanup, looks good.
  pablomartin4btc:
    ACK fa3f682
  naiyoma:
    ACK fa3f682

Tree-SHA512: 5b1fc003b5bea4f98c1b79376b06f5565ccddaf6b4969e1b16f1225755e1c68a5fde3ccafa86d2923a92aa8a8f9c47dfd048be2ff705d7269664188cf11da3f4

Author: fanquake

test/functional/test_framework/mempool_util.py

@@ -57,8 +57,7 @@ def fill_mempool(test_framework, node, *, tx_sync_fun=None):
     """Fill mempool until eviction.
 
     Allows for simpler testing of scenarios with floating mempoolminfee > minrelay
-    Requires -maxmempool=5 and assumes -minrelaytxfee
-    is 1 sat/vbyte.
+    Requires -maxmempool=5.
     To avoid unintentional tx dependencies, the mempool filling txs are created with a
     tagged ephemeral miniwallet instance.
     """