This reverts commit 6a93b17c8cafc1d8e1c52e133511e52ed9086355.
The reverted commit added more complexity than it was worth at the
current stage. Handling delta CapVer changes requires extensive changes
to relayManager datastructures in order to also support delta updates of
relay servers.
Updates tailscale/corp#27502
Signed-off-by: Jordan Whited <jordan@tailscale.com>