[python] reopen test case

[msyyc]

Reopen test case for https://github.com/microsoft/typespec/blob/5d549c414f9a359fd768f5130de4f029c8cb67f9/packages/http-client-python/generator/test/generic_mock_api_tests/test_encode_bytes.py and

typespec/packages/http-client-python/generator/test/generic_mock_api_tests/asynctests/test_encode_bytes_async.py

Lines 127 to 128 in 5d549c4

	# will reopen after TCGC release a fix version for https://github.com/Azure/typespec-azure/pull/2411
	# assert expected == await client.response_body.base64_url()

with reference of Azure/autorest.python#3253.

NOTE:

• DO add changelog