com.google.cloud.opentelemetry:auto-exporter is logging the service account access token

[vgonsalv]

When using the auto-exporter along-side the standard OpenTelmetry Java agent (link), the Service Account access token is being logged.

This is a security issue, as it allows anyone with access to the logs to be able to impersonate the service.

The desired fix is that this token not be logged at all.

[dashpole]

@psx95 can you look into this?