health: Only overwrite probes with newer reports
health: Only overwrite probes with newer reports

Previously, we would unconditionally update the API-visible cluster
health report in the server, even if the probe was performed earlier
than the currently visible report. This could happen if, for instance, a
periodic probe began and was unable to complete, then a manual probe was
invoked via the API (which succeeds and updates the server's cache),
then finally the periodic probe completes.

Check the start time of the probe and only overwrite if the probe is newer.

Fixes: #2956

Signed-off-by: Joe Stringer <16a9a54ddf4259952e3c118c763138e83693d7fd@covalent.io>

tgraf/cilium,eloycoto/cilium,cilium-team/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,cilium-team/cilium,scanf/cilium,cilium/cilium,eloycoto/cilium,michi-covalent/cilium,cilium/cilium,tklauser/cilium,tgraf/cilium,tgraf/cilium,scanf/cilium,scanf/cilium,michi-covalent/cilium,eloycoto/cilium,tklauser/cilium,tklauser/cilium,scanf/cilium,eloycoto/cilium,cilium/cilium,tgraf/cilium,tklauser/cilium,scanf/cilium,tgraf/cilium,scanf/cilium,tklauser/cilium,michi-covalent/cilium,eloycoto/cilium,scanf/cilium,eloycoto/cilium,michi-covalent/cilium,tgraf/cilium,eloycoto/cilium