Use GOOGLE_OAUTH_ACCESS_TOKEN to make it work with workload identity service account without key

[Maarc-D]

Describe the solution you'd like
Be able to use directly token from environment variable GOOGLE_OAUTH_ACCESS_TOKEN

Additional context
In a case using workload identity and gitlab federation the connection is made by :

echo $GITLAB_OIDC_TOKEN > .tmp_test_sa_nokey_file
gcloud iam workload-identity-pools create-cred-config projects/${GOOGLE_PROJECT_NUMBER}/locations/global/workloadIdentityPools/${GOOGLE_WORKLOAD_IDENTITY_POOL_ID}/providers/${GOOGLE_WORKLOAD_IDENTITY_POOL_PROVIDER_ID} --service-account=${GOOGLE_SERVICE_ACCOUNT_EMAIL} --output-file=.tmp_test_sa_nokey_file_credentials.json --credential-source-file=.tmp_test_sa_nokey_file
gcloud auth login --cred-file=`pwd`/.tmp_test_sa_nokey_file_credentials.json --update-adc
export GOOGLE_OAUTH_ACCESS_TOKEN="$(gcloud auth print-access-token)"

But with actual code we got : got error: Get "https://compute.googleapis.com/compute/v1/projects/[MASKED]/aggregated/instances?alt=json&prettyPrint=false": oauth2/google: unable to generate access token: Post "https://iamcredentials.googleapis.com/v1/projects/-/serviceAccounts/[MASKED]@[MASKED]:generateAccessToken": oauth2/google/externalaccount: failed to open credential file ".tmp_test_sa_nokey_file"