Reduce amount of logs in decentralized_hive_fund_tests (log sizes are too large)

Some of the tests in decentralized_hive_fund_tests produces around 90k blocks which results in a large size of p2p.log and stderr.txt logs that weighs excessively around 500mb compressed. Fixture introduced in this commit overrides the default node fixture to reduce the size of the logs, by setting the problematic loggers to a higher log level.