Investigate/replace GlobalParserTLS thread local

[ormsbee]

Ensure this is async-safe:

openedx-platform/openedx/core/lib/safe_lxml/xmlparser.py

Lines 68 to 75 in 628c980

	class GlobalParserTLS(threading.local):
	"""Thread local context for custom parser instances"""
	parser_config = {
	"resolve_entities": False,
	}
	element_class = RestrictedElement