qa: fix deprecated log.warn in feature_dbcrash test
Summary:
This clears up the following deprecation message when running the test:
test/functional/feature_dbcrash.py:270: DeprecationWarning: The 'warn'
method is deprecated, use 'warning' instead
self.log.warn("Node %d never crashed during utxo flush!", i)
Git grepping indicates that this was the last remaining use of
`log.warn` in the functional tests.Backport of core PR16491:
https://github.com/bitcoin/bitcoin/pull/16491/files
Test Plan:
./test/functional/test_runner.py feature_dbcrash
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D4564