Fix E2E test failures for Cloud Run v2, KMS, Compute VM, and update GEMINI.md (#3953)

* Update Cloud Run v2 GPU examples in README

Remove launch_stage = "BETA" from examples as it now defaults to GA in the provider. This fixes E2E test failures where the API returns GA. Reference: https://github.com/hashicorp/terraform-provider-google/pull/17029

TAG=agy

* Fix KMS and Compute VM E2E test failures

Update README examples to avoid conflicts and unsupported modes, and update corresponding inventories.

TAG=agy

* Add instruction to run a single specific example test in GEMINI.md

TAG=agy

modules/kms/README.md

@@ -57,7 +57,7 @@ module "kms" {
         key-b-iam1 = {
           key    = "key-b"
           member = "group:${var.group_email}"
-          role   = "roles/cloudkms.cryptoKeyEncrypterDecrypter"
+          role   = "roles/cloudkms.viewer"
         }
       }
     }