Update google-protobuf and remove workaround

In order to comply with the no-unsafe-eval CSP, we worked around issue
https://github.com/protocolbuffers/protobuf/issues/6770 by including a
modified version of google-protobuf under the src/third_party folder.

This CL updates the google-protobuf version to one which fixes this bug,
and removes the workaround.

Change-Id: Ida7943bad452ee930defbc136602a34910a41977
diff --git a/src/killSwitch/api_proto/kill_switch_objects_pb.js b/src/killSwitch/api_proto/kill_switch_objects_pb.js
index 4b3d6e6..427daa5 100644
--- a/src/killSwitch/api_proto/kill_switch_objects_pb.js
+++ b/src/killSwitch/api_proto/kill_switch_objects_pb.js
@@ -17,7 +17,7 @@
 
 var api_proto_common_pb = require('../api_proto/common_pb.js');
 goog.object.extend(proto, api_proto_common_pb);
-var google_protobuf_timestamp_pb = require('../../third_party/google-protobuf-commonjs_strict/google/protobuf/timestamp_pb.js');
+var google_protobuf_timestamp_pb = require('google-protobuf/google/protobuf/timestamp_pb.js');
 goog.object.extend(proto, google_protobuf_timestamp_pb);
 goog.exportSymbol('AuthorizedUserTransformation', null, proto);
 goog.exportSymbol('Feature', null, proto);