SP reset timeout may be too short and should be runtime configurable

[jgallagher]

We currently override whatever retry attempt is configured specifically for SP resets:

management-gateway-service/gateway-sp-comms/src/single_sp.rs

Lines 1979 to 1985 in ca9f20e

	// See comment on `SP_RESET_TIME_ALLOWED` above; bump up the retry count
	// if we're trying to trigger an SP reset.
	let calc_reset_attempts = || {
	let time_desired = SP_RESET_TIME_ALLOWED.as_millis();
	let per_attempt = self.per_attempt_timeout.as_millis().max(1);
	((time_desired + per_attempt - 1) / per_attempt) as usize
	};

to allow up to 30 seconds, particularly for sidecar SPs which have historically taken "a while".

We saw a sidecar SP reset timeout today during a mupdate, and a subsequent retry succeeded but took 25 seconds. A likely explanation for the timeout is that there's some variance and 30 seconds was just too short. We should bump this 30 seconds up, and ideally also allow reset timeouts to be configured at runtime like the retry timeouts are for every other command.