gsutil ls and cp commands fail for public files in GKE environemnts

Here is a simple command that verifies the presence of a public GCS file:
```
gsutil ls gs://ml-pipeline-dataset/Chicago_taxi_trips/chicago_taxi_trips_2019-01-01_-_2019-02-01_limit=10000.csv
```

However, when the script is running on GKE, the command fails:
```
PreconditionException: 412 The type of authentication token used for this request requires that Uniform Bucket Level Access be enabled.
```

Please fix the `gsutil ls` command such that it can work on public buckets regardless of the environment.

--
Thank you.
Alexey Volkov

Start by reproducing the `gsutil ls` command from the issue in a GKE environment and compare it with behavior outside GKE. Trace the authentication handling for public GCS access, then add coverage for public `ls` and `cp` commands; done means both commands work for public buckets regardless of environment.

Written by the indexing model from the issue text.