docs(samples): Update slates and CDN keys to use LROs

[irataxy]

BEGIN_COMMIT_OVERRIDE
docs(samples): Update slates and CDN keys to use LROs
docs(samples): Add samples for live config and live session
END_COMMIT_OVERRIDE

Please merge on approval.

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• Appropriate docs were updated (if necessary)

Fixes b:277359252

[snippet-bot]

Here is the summary of changes.

You are about to add 4 region tags.

• samples/snippets/create_live_config.py:25, tag videostitcher_create_live_config
• samples/snippets/delete_live_config.py:23, tag videostitcher_delete_live_config
• samples/snippets/get_live_config.py:23, tag videostitcher_get_live_config
• samples/snippets/list_live_configs.py:22, tag videostitcher_list_live_configs

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