mount helper does not work with federated workload identity

I am not able to get mount helper to work with federated workload identity. Just running gcsfuse works fine on the same system. Outputs below.

```
mount -t gcsfuse velen-wp-uploads-germany /tmp/bucket
Calling gcsfuse with arguments: -o rw velen-wp-uploads-germany /tmp/bucket
2022/04/28 13:40:52.056394 Start gcsfuse/v0.41.0 (Go version go1.18.1) for app "" using mount point: /tmp/bucket
2022/04/28 13:40:52.067447 Opening GCS connection...

```
terminal stalls for a few minutes

then prints this message

```
2022/04/28 13:43:43.084844 Failed to open connection: GetTokenSource: DefaultTokenSource: google: could not find default credentials. See https://developers.google.com/accounts/docs/application-default-credentials for more information.
daemonize.Run: readFromProcess: sub-process: mountWithArgs: getConnWithRetry: GetTokenSource: DefaultTokenSource: google: could not find default credentials. See https://developers.google.com/accounts/docs/application-default-credentials for more information.
running gcsfuse: exit status 1

```

On the same system i am able to mount using the gcsfuse command
```
gcsfuse velen-wp-uploads-germany /tmp/bucket
2022/04/28 13:39:41.808885 Start gcsfuse/v0.41.0 (Go version go1.18.1) for app "" using mount point: /tmp/bucket
2022/04/28 13:39:41.820575 Opening GCS connection...
2022/04/28 13:39:42.050355 Mounting file system "velen-wp-uploads-germany"...
2022/04/28 13:39:42.050891 File system has been successfully mounted.
root@ip-10-200-1-18:/# ls /tmp/bucket
'Image from iOS (13).gif'
```