Merge bitcoin/bitcoin#29500: test: create assert_not_equal util

7bb83f6718 test: create assert_not_equal util and add to where imports are needed (kevkevin)

Pull request description:

  In the functional tests there are lots of cases where we assert != which we now swap with assert_not_equal to be more readable

  This is motivated/uses logic from this PR which was closed https://github.com/bitcoin/bitcoin/pull/28528
  This partially helps https://github.com/bitcoin/bitcoin/issues/23119

  I've broken it up to just `assert_not_equal` to keep the PR smaller as suggested in https://github.com/bitcoin/bitcoin/pull/28528#issuecomment-1959945805

  I can create follow up PR's if this is wanted

ACKs for top commit:
  hodlinator:
    re-ACK 7bb83f6718
  ryanofsky:
    Code review ACK 7bb83f6718. Only change since last review is fixing error message formatting and passing it as a keyword argument
  janb84:
    Re-ACK [7bb83f6](https://github.com/bitcoin/bitcoin/commit/7bb83f6718110cb3a29e72522fdc5515db21c7d0)

Tree-SHA512: de09f41a690033a5b61e6f861d3bd69a32b889d6655a28fbc0d5cfac9f7ec9c642432967d33913970882b4cfdd47bdd377d0ddc44e25976cbaa49f7f9d8f7b10

test/functional/feature_assumeutxo.py

@@ -36,6 +36,7 @@ from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_approx,
     assert_equal,
+    assert_not_equal,
     assert_raises_rpc_error,
     ensure_for,
     sha256sum_file,
@@ -476,7 +477,7 @@ class AssumeutxoTest(BitcoinTestFramework):
         assert_equal(
             dump_output4['txoutset_hash'],
             "8a1db0d6e958ce0d7c963bc6fc91ead596c027129bacec68acc40351037b09d7")
-        assert sha256sum_file(dump_output['path']) != sha256sum_file(dump_output4['path'])
+        assert_not_equal(sha256sum_file(dump_output['path']), sha256sum_file(dump_output4['path']))
 
         # Use a hash instead of a height
         prev_snap_hash = n0.getblockhash(prev_snap_height)