Merge bitcoin/bitcoin#31406: test: fix test_invalid_tx_in_compactblock in p2p_compactblocks

7239ddb test: make sure node has all transactions (brunoerg)
ee1b9be test: replace `is not` to `!=` when comparing block hash (brunoerg)

Pull request description:

  `test_invalid_tx_in_compactblock` tests that we don't get disconnected if we relay a compact block with valid header, but invalid transactions.

  In this test, after sending the block with invalid transactions, this test checks two things: the tip in the receiver node did not advance and the sender did not get disconnected. However, even if the block contains only valid transactions, the tip would not advance because the receiver does not have all transactions to reconstruct the valid and would request them back. This PR fixes it by sending all the transactions.

  Also, comparing block hash (int) using `is not` can lead to subtle bugs, this PR fixes it by replacing it to `!=`.

  --------------

  Can be tested by applying:
  ```diff
  diff --git a/test/functional/p2p_compactblocks.py b/test/functional/p2p_compactblocks.py
  index 274ef9532c..419153a32f 100755
  --- a/test/functional/p2p_compactblocks.py
  +++ b/test/functional/p2p_compactblocks.py
  @@ -723,11 +723,8 @@ class CompactBlocksTest(BitcoinTestFramework):
           utxo = self.utxos[0]

           block = self.build_block_with_transactions(node, utxo, 5)
  -        del block.vtx[3]
           block.hashMerkleRoot = block.calc_merkle_root()
           # Drop the coinbase witness but include the witness commitment.
  -        add_witness_commitment(block)
  -        block.vtx[0].wit.vtxinwit = []
           block.solve()

           # Make sure node has the transactions to reconstruct the block
  ```

ACKs for top commit:
  instagibbs:
    ACK 7239ddb
  glozow:
    ACK 7239ddb
  lucasbalieiro:
    Tested ACK for commit [7239ddb](bitcoin/bitcoin@7239ddb)

Tree-SHA512: 6d04fb7c50b5e635c83ede75c12130cbd8e1b229887a86a2e1bfe747e4208731faecc7265cae063c1ace187b20c5f37080d5116760766fa2948f38971e5f6fbf

Author: glozow

test/functional/p2p_compactblocks.py

@@ -733,12 +733,12 @@ def test_invalid_tx_in_compactblock(self, test_node):
         # Now send the compact block with all transactions prefilled, and
         # verify that we don't get disconnected.
         comp_block = HeaderAndShortIDs()
-        comp_block.initialize_from_block(block, prefill_list=[0, 1, 2, 3, 4], use_witness=True)
+        comp_block.initialize_from_block(block, prefill_list=list(range(len(block.vtx))), use_witness=True)
         msg = msg_cmpctblock(comp_block.to_p2p())
         test_node.send_and_ping(msg)
 
         # Check that the tip didn't advance
-        assert int(node.getbestblockhash(), 16) is not block.sha256
+        assert int(node.getbestblockhash(), 16) != block.sha256
         test_node.sync_with_ping()
 
     # Helper for enabling cb announcements