fix: delete deprecated product samples

[iennae]

Description

Fixes #

Checklist

Testing

• I have tested this change on a live environment and verified it works as intended.

Compliance & Style

• I have followed the Sample Guidelines.
• The README is updated with all relevant information (if applicable).
• If this PR adds a new sample directory: I updated the CODEOWNERS file.

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Post-Approval Actions

• Please merge this PR for me once it is approved

[snippet-bot]

Here is the summary of changes.

You are about to delete 20 region tags.

• datacatalog/quickstart/quickstart.py:18, tag data_catalog_quickstart
• datacatalog/quickstart/quickstart.py:41, tag data_catalog_quickstart
• datacatalog/snippets/create_custom_entry.py:18, tag data_catalog_create_custom_entry
• datacatalog/snippets/create_custom_entry.py:39, tag data_catalog_create_custom_entry
• datacatalog/snippets/create_fileset.py:18, tag data_catalog_create_fileset
• datacatalog/snippets/create_fileset.py:37, tag data_catalog_create_fileset
• datacatalog/snippets/data_catalog_ptm_create_taxonomy.py:15, tag data_catalog_ptm_create_taxonomy
• datacatalog/snippets/grant_tag_template_user_role.py:18, tag data_catalog_grant_tag_template_user_role
• datacatalog/snippets/grant_tag_template_user_role.py:40, tag data_catalog_grant_tag_template_user_role
• datacatalog/snippets/lookup_entry.py:20, tag data_catalog_lookup_dataset
• datacatalog/snippets/lookup_entry.py:21, tag data_catalog_lookup_entry
• datacatalog/snippets/lookup_entry.py:44, tag data_catalog_lookup_entry
• datacatalog/snippets/search_assets.py:18, tag data_catalog_search_assets
• datacatalog/snippets/search_assets.py:36, tag data_catalog_search_assets
• datacatalog/v1beta1/create_entry_group.py:17, tag data_catalog_create_entry_group_v1beta1
• datacatalog/v1beta1/create_fileset_entry.py:17, tag data_catalog_create_fileset_v1beta1
• datacatalog/v1beta1/get_entry.py:29, tag data_catalog_get_entry_v1beta1
• datacatalog/v1beta1/lookup_entry.py:27, tag data_catalog_lookup_entry_v1beta1
• datacatalog/v1beta1/lookup_entry_sql_resource.py:27, tag data_catalog_lookup_entry_sql_resource_v1beta1
• datacatalog/v1beta1/search.py:29, tag data_catalog_search_v1beta1

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[gemini-code-assist]

Code Review

This pull request removes all Python code samples, test suites, and requirements files associated with the deprecated Data Catalog API (v1 and v1beta1) in preparation for its decommissioning. I have no feedback to provide.