1. merge endpoint picking and localility picking policy to one field in cluster_resolver's balancer config
- This field only supports ROUND_ROBIN or RING_HASH.
- This is to support RING_HASH policy, which is responsible both endpoint picking and locality picking.
- If policy is RING_HASH, endpoints in localities will be flattened to a list of endpoints, and passed to the policy.
1. support building policy config with RING_HASH as a child
- The config tree has one less layer comparing with ROUND_ROBIN
- This also need to define RING_HASH's balancer config config
1. Deleted test `TestEDS_UpdateSubBalancerName` because now the balancer doesn't support updating child to a custom policy.
golint does check for missing package comment, but with low confidence.
golint checks each file, and complains on every file missing package comment, even though another file in the same package has the comment.
This PR adds a golint check with low min_confidence, and filters out false-positives.
Doug Fawley
Menghan Li
Easwar Swaminathan