fix(api-client): Prevent ZodError on Sentry API 400 in validateEvents

[sentry]

This PR addresses issue MCP-SERVER-G3K, where SentryApiService.validateEvents was throwing a ZodError when the Sentry API returned a 400 Bad Request.

The root cause was that allowStatuses: [400] was explicitly passed to this.request, which prevented the 400 HTTP response from being thrown as an ApiError. Instead, the error payload (e.g., {"detail": "..."}) was returned as a successful response body and then passed to EventsValidationResponseSchema.parse, leading to a Zod validation failure.

The fix involves removing allowStatuses: [400] from the this.request call within validateEvents. This ensures that 400 Bad Request responses from the Sentry API are correctly handled as errors, throwing an ApiError as expected, and preventing the malformed payload from reaching the Zod schema parser.

Fixes MCP-SERVER-G3K

_{Comment @sentry <feedback> on this PR to have Autofix iterate on the changes.}