chore: Update region tags

[arbrown]

Removing unused region tags not associated with a product and not used in documentation.

Sample code that is part of a larger sample is remaining in this file.

Adding product prefix to wait_for_operation as it is referenced in documentation.

Description

Fixes #

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Checklist

• [x] I have followed Sample Guidelines from AUTHORING_GUIDE.MD
• [x] README is updated to include all relevant information
• [ ] Tests pass: nox -s py-3.9 (see Test Environment Setup)
• [ ] Lint pass: nox -s lint (see Test Environment Setup)
• [ ] These samples need a new API enabled in testing projects to pass (let us know which ones)
• [ ] These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• [ ] This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• [ ] This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• [x] Please merge this PR for me once it is approved

[snippet-bot[bot]]

Here is the summary of changes.

You are about to add 1 region tag.

- [compute/api/create_instance.py:167](https://github.com/GoogleCloudPlatform/python-docs-samples/blob/d1822704b8199f7e95ecfa0f0f176f0ddde15ec3/compute/api/create_instance.py#L167), tag `compute_wait_for_operation`

You are about to delete 3 region tags.

- [compute/api/create_instance.py:34](https://github.com/GoogleCloudPlatform/python-docs-samples/blob/a1aa50980f978170e0ffcd5b2851fbe7123b7960/compute/api/create_instance.py#L34), tag `list_instances` - [compute/api/create_instance.py:149](https://github.com/GoogleCloudPlatform/python-docs-samples/blob/a1aa50980f978170e0ffcd5b2851fbe7123b7960/compute/api/create_instance.py#L149), tag `delete_instance` - [compute/api/create_instance.py:213](https://github.com/GoogleCloudPlatform/python-docs-samples/blob/a1aa50980f978170e0ffcd5b2851fbe7123b7960/compute/api/create_instance.py#L213), tag `run`

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