Runner metrics cover the full macOS job, even on long runs

Long Tuist macOS CI jobs no longer have their metrics charts cut off mid-run. Tart-kubelet now issues runner service-account tokens with an 8-hour TTL (up from 1 hour), so the in-VM metrics sampler keeps POSTing for the whole job instead of getting 401s once the warm token ages out. The macOS runner image also runs a synchronous NTP step right after dispatch succeeds, so step timestamps and metric samples share one timeline on freshly booted VMs rather than re-aligning only as timed corrects the clock mid-run. Both fixes take effect for jobs run after the tart-kubelet and runner-image rollouts reach the fleet.