chore: delete unused code

[sofisl]

Delete unused code

[snippet-bot[bot]]

Here is the summary of changes.

You are about to delete 13 region tags.

- [samples/generated/v1/cloud_billing.create_billing_account.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_billing.create_billing_account.js#L24), tag `cloudbilling_v1_generated_CloudBilling_CreateBillingAccount_async` - [samples/generated/v1/cloud_billing.get_billing_account.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_billing.get_billing_account.js#L24), tag `cloudbilling_v1_generated_CloudBilling_GetBillingAccount_async` - [samples/generated/v1/cloud_billing.get_iam_policy.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_billing.get_iam_policy.js#L24), tag `cloudbilling_v1_generated_CloudBilling_GetIamPolicy_async` - [samples/generated/v1/cloud_billing.get_project_billing_info.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_billing.get_project_billing_info.js#L24), tag `cloudbilling_v1_generated_CloudBilling_GetProjectBillingInfo_async` - [samples/generated/v1/cloud_billing.list_billing_accounts.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_billing.list_billing_accounts.js#L24), tag `cloudbilling_v1_generated_CloudBilling_ListBillingAccounts_async` - [samples/generated/v1/cloud_billing.list_project_billing_info.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_billing.list_project_billing_info.js#L24), tag `cloudbilling_v1_generated_CloudBilling_ListProjectBillingInfo_async` - [samples/generated/v1/cloud_billing.set_iam_policy.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_billing.set_iam_policy.js#L24), tag `cloudbilling_v1_generated_CloudBilling_SetIamPolicy_async` - [samples/generated/v1/cloud_billing.test_iam_permissions.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_billing.test_iam_permissions.js#L24), tag `cloudbilling_v1_generated_CloudBilling_TestIamPermissions_async` - [samples/generated/v1/cloud_billing.update_billing_account.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_billing.update_billing_account.js#L24), tag `cloudbilling_v1_generated_CloudBilling_UpdateBillingAccount_async` - [samples/generated/v1/cloud_billing.update_project_billing_info.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_billing.update_project_billing_info.js#L24), tag `cloudbilling_v1_generated_CloudBilling_UpdateProjectBillingInfo_async` - [samples/generated/v1/cloud_catalog.list_services.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_catalog.list_services.js#L24), tag `cloudbilling_v1_generated_CloudCatalog_ListServices_async` - [samples/generated/v1/cloud_catalog.list_skus.js:24](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/generated/v1/cloud_catalog.list_skus.js#L24), tag `cloudbilling_v1_generated_CloudCatalog_ListSkus_async` - [samples/quickstart.js:21](https://github.com/googleapis/nodejs-billing/blob/b8da1ebd2fb489ef6a63e08467667f0f8b41685c/samples/quickstart.js#L21), tag `billing_quickstart`

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Warning: This pull request is touching the following templated files:

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