remove references to "server.socket" file
remove references to "server.socket" file

The C++ client now talks to the Java server through protobuf messages
using the RPC mechanism provided by grpc, so this AF_UNIX socket file is
not used anymore for the communication between them since commit
a3c4833dc24b: ("Remove support for using AF_UNIX...").

--
Change-Id: Ic71e4c65ebb6bb2e661128635c2440007feaf5f6
Reviewed-on: https://bazel-review.googlesource.com/#/c/7030/
MOS_MIGRATED_REVID=137679905

bazelbuild/bazel-website,davidzchen/bazel-website,davidzchen/bazel-website,bazelbuild/bazel-website,bazelbuild/bazel-website,davidzchen/bazel-website,davidzchen/bazel-website