ref: Begin deprecating category from localities

[lynnagara]

No longer required, visibility is controlled via visible and signup_visible parameters

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[sentry]

Bug: Removing the category check in find_all_multitenant_locality_names may incorrectly expose single-tenant localities in the UI if they are configured with visible=True.
_{Severity: HIGH}

Suggested Fix

Verify that all production configurations for single-tenant localities have been updated to set visible=False. To mitigate risk, consider adding logging to detect and alert on any single-tenant localities with visible=True during a transition period. Ensure the breaking nature of this change is clearly communicated.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: src/sentry/types/cell.py#L498-L499

Potential issue: The function `find_all_multitenant_locality_names` was changed to
filter localities solely based on the `visible` flag, removing the previous check for
`category == RegionCategory.MULTI_TENANT`. This change assumes that all single-tenant
localities in production configurations have been updated to `visible=False`. If any
single-tenant locality is configured with `visible=True`, it will now be incorrectly
exposed in the frontend UI and included in DNS prefetching. This represents a breaking
change and a migration risk, as the required configuration updates are not mentioned or
enforced, potentially leading to unintended exposure of single-tenant environments.

Also affects:

• src/sentry/web/client_config.py:367~372