Fix environment for protobuf compilation in grpc

Add use_default_shell_env = True to protoc invocation for grpc to mirror
what the protobuf cc_proto_library & co are doing
Fixes a failure in invocing protoc when it is build in a non-default
environment (e.g. with a custom LD_LIBRARY_PATH)

Fixes #11852, fixes #11855

third_party/grpc/bazel/generate_cc.bzl

diff --git a/third_party/grpc/bazel/generate_cc.bzl b/third_party/grpc/bazel/generate_cc.bzl
index 7b4c1aa..8e6fcd6 100644
--- a/third_party/grpc/bazel/generate_cc.bzl
+++ b/third_party/grpc/bazel/generate_cc.bzl
@@ -124,6 +124,7 @@
         outputs = out_files,
         executable = ctx.executable.protoc,
         arguments = arguments,
+        use_default_shell_env = True,
     )
 
     return struct(files = depset(out_files))