ref(eap): make trace item attributes alias test less fragile

[mjq]

OrganizationTraceItemAttributesEndpointSpansTest::test_aliased_attribute in tests/snuba/api/endpoints/test_organization_trace_item_attributes.py revealed itself to be fragile in #116509, when adding new attributes suddenly broke its assertions around op aliases:

sentry/tests/snuba/api/endpoints/test_organization_trace_item_attributes.py

Lines 904 to 906 in 61bc60a

	# These two are unrelated, but happen to match.
	assert "db.operation" in keys
	assert "db.operation.name" in keys

Update the test to be less fragile, focusing on the presence or absence of op aliases rather than complete keys results.