Introduce simplified Default credential provision

As the first step in credential consolidation, we replace
injection of application default credential in for KMS and
Drive.

Tests:
- for Drive, tested with exportDomainLists and exportReservedTerms.
- For KMS, used CLI commands (get_keyring_secret and update_kms_keyring) to change and
  restore secret for one key.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=211819859

java/google/registry/config/BUILD

@@ -10,6 +10,7 @@ java_library(
     resources = glob(["files/*.yaml"]),
     deps = [
         "//java/google/registry/util",
+        "@com_google_api_client",
         "@com_google_appengine_api_1_0_sdk",
         "@com_google_auto_value",
         "@com_google_code_findbugs_jsr305",