This is a refinement of #19916. Previously, we would only emit a latency log
when going from a cached netmap to an uncached one (i.e., from the control
plane). We would like to know the latency in both conditions, though, so
instead use the validity of the previous self state.
Updates #12639
Updates tailscale/projects#27
Change-Id: I6bbeb5d3162f1f98cdb3dcd244f67ef31c170957
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
eda975a9e4