DRIVERS-2601 Fix API description for GCP built-in OIDC provider

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Please complete the following before merging:

• [x] Update changelog.
• [ ] Make sure there are generated JSON files from the YAML test files.
• [x] Test changes in at least one language driver.
• [ ] Test these changes against all server versions and topologies (including standalone, replica set, sharded clusters, and serverless).

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Passing test for pymongo: https://spruce.mongodb.com/task/mongo_python_driver_testgcpoidc_variant_oidc_auth_test_gcp_latest_patch_79fb19c1a6e293278f5385b49b0c59740b5c571a_66270244f907a20007657216_24_04_23_00_35_29/logs?execution=0