Changes the default alias names to role_id for both IAM and GCE authn

[austingebauer]

Overview

This PR changes the default name of the entity alias that gets created for both IAM and GCE authentication. Test fixes are also included in this PR. See test output below.

For IAM, changes it from unique_id to role_id.
For GCE, change it from instance_id to role_id.

Docs PR: hashicorp/vault#9494

Design of Change

Change was implemented using alias configuration made available in #89.

Related Issues/Pull Requests

• Add alias types for IAM and GCE logins #89

Contributor Checklist

• Add relevant docs to upstream Vault repository, or sufficient reasoning why docs won’t be added yet
• Backwards compatible
  • This is an intentional change that will be included in a CHANGES entry in the Vault CHANGELOG.
• Add output for any tests not ran in CI to the PR description (eg, acceptance tests)

$ export GOOGLE_CREDENTIALS="$(cat /Users/austingebauer/.gcp/austin-gebauer-db62ff1c96b4.json)"
$ make test                                                                                    
?       github.com/hashicorp/vault-plugin-auth-gcp      [no test files]
ok      github.com/hashicorp/vault-plugin-auth-gcp/plugin       (cached)
?       github.com/hashicorp/vault-plugin-auth-gcp/plugin/cache [no test files]
$ echo $?
0