This PR removes the `ids` query parameter from the `GET /extensions`
endpoint, as we don't use it.

We originally added the query parameter in #9929 to facilitate
auto-updates. However, it was superseded by the `GET
/extensions/updates` endpoint in #10052.

There shouldn't be any Zed versions out in the wild that are using the
`ids` query parameter, as we added the endpoint on Thursday, March 28,
and replaced its usage with the new endpoint on Monday, April 1, before
the next Zed release.

Release Notes:

- N/A