instr(server): Use project_key instead of org_id

[jjbayer]

Follow-up to #4397: As I could have known, the organization ID is not available in the request handler:

relay/relay-server/src/extractors/request_meta.rs

Lines 398 to 400 in b28929c

	/// The scoping returned from this function is not complete since it lacks info from the Project
	/// state. To fetch full scoping information, invoke the `GetScoping` message on `Project`.
	pub fn get_partial_scoping(&self) -> Scoping {

#skip-changelog