* stable-2.15:
ElasticContainer: Use Elasticsearch 6.4.1 for V6_4 tests
AbstractDaemonTest: Don't delete common server path too early
Fix toolchain definitions for bazel 0.17.1
Bazel: Bump baseline to 0.17.1
Change-Id: Ic1217b4ed7495eb325cb73cfb453775e61a1181b