fix(search): Reject unsupported project inbox sorts

[cvxluo]

Inbox sorting is implemented only by organization issue search, so remove its project API documentation and generic executor registration.

Project requests now return 400 instead of sending an empty aggregation name to Snuba.

Fixes SENTRY-5N94

[sentry]

Bug: Removing inbox from sort_strategies without adding API-level validation can cause a KeyError when sort_by='inbox' is passed, as the code directly accesses self.sort_strategies[sort_by].
_{Severity: HIGH}

Suggested Fix

Add validation at the API layer, likely in build_query_params_from_request(), to ensure the sort parameter is one of the allowed values defined in the OpenAPI specification. This will reject invalid sort options like inbox before they reach the query executor, preventing the KeyError.

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/search/snuba/executors.py#L1248-L1250

Potential issue: The pull request removes the `"inbox"` key from the
`PostgresSnubaQueryExecutor.sort_strategies` dictionary. However, there is no
corresponding input validation at the API layer to prevent clients from sending
`sort=inbox`. When an API request like `GET
/api/projects/{org}/{project}/issues/?sort=inbox` is made, the `sort_by` parameter
reaches the executor. The code then attempts to access `self.sort_strategies["inbox"]`,
which results in an unhandled `KeyError` because the key no longer exists. The existing
fallback logic does not handle this case, leading to a server error.

Also affects:

• src/sentry/apidocs/parameters.py:408~414

_{Did we get this right? 👍 / 👎 to inform future reviews.}