Support changing the logging level

[suhaibmujahid]

We have many files where the login level is hardcoded at the module level, making it difficult to change it as needed.

Examples:

bugbug/scripts/microannotate_generator.py

Lines 14 to 15 in c3b6696

	basicConfig(level=INFO)
	logger = getLogger(__name__)

bugbug/scripts/shadow_scheduler_stats.py

Lines 22 to 23 in c3b6696

	logging.basicConfig(level=logging.INFO)
	logger = logging.getLogger(__name__)