* Tackle #4929 a different way
This turns c.sealed into an atomic, which allows us to call sealInternal
without a lock. By doing so we can better control lock grabbing when a
condition causing the standby loop to get out of active happens. This
encapsulates that logic into two distinct pieces (although they could
be combined into one), and makes lock guarding more understandable.
* Re-add context canceling to the non-HA version of sealInternal
* Return explicitly after stopCh triggered
