AteletDialer caches one grpc.ClientConn per atelet pod UID in a
1024-entry LRU with no eviction function, so a conn pushed out to make
room was forgotten, never closed. grpc does not reclaim an un-Closed
conn: its goroutines and buffers stay alive for the life of the process.
Close evicted conns via the cache's eviction hook, the same fix the
atelet ateom dialer received.
Fixes#470
> It's a good idea to open an issue first for discussion.
- [ ] Tests pass
- [x] Appropriate changes to documentation are included in the PR
Da Huang
e2092d0e68