_sandboxremote.py: Include details in UNAVAILABLE error logging
Description
Currently, it can be quite unclear what is causing the UNAVAILABLE error reported as "Failed contacting remote execution server at URL". This MR provides more information to the user about potential issues reported in the GRPC error but were not logged.
Changes proposed in this merge request:
- Remove special log case for UNAVAILABLE
This merge request, when approved, will close: #1392 (closed)