Fix suppressKeyFileNotice for impersonated ADC credentials

[nickjenkin]

When using impersonated ADC credentials with the PHP SDK, an error is thrown:

A keyfile was given, but it does not contain a project ID. This can indicate an old and obsolete keyfile, in which case you should create a new one. To suppress this message, set suppressKeyFileNotice to true in your client configuration. To learn more about generating new keys, see this URL: https://cloud.google.com/iam/docs/creating-managing-service-account-keys#creating_service_account_keys

Setting suppressKeyFileNotice=>true allows the impersonated ADC credentials to work. However this check is for old service accounts, and should be modified to account for impersonated credential files.

Environment details

• OS: Linux
• PHP version: 8.4.7
• Package name and version: Core/src
  /ClientTrait.php

Steps to reproduce

1. Use an impersonated ADC credential e.g. "gcloud auth application-default login --impersonate-service-account=..."
2. (Docker) Set:GOOGLE_APPLICATION_CREDENTIALS=~/.config/gcloud/application_default_credentials.json and
   GOOGLE_CLOUD_PROJECT=xyz

Code example

Errors:

        $storage = new StorageClient();

Works:

        $storage = new StorageClient(['suppressKeyFileNotice' => true]);