tracking liveness of pt-osc from outside the execution flow, so we can identify an execution running 'from the outside', e.g. if the vttablet that spawned pt-osc crashed. Cancelling a migration also based on that and is more robust
tracking liveness of pt-osc from outside the execution flow, so we can identify an execution running 'from the outside', e.g. if the vttablet that spawned pt-osc crashed. Cancelling a migration also based on that and is more robust

Signed-off-by: Shlomi Noach <f07557902aa82e6b2846c90bd293a06970411e12@users.noreply.github.com>

tinyspeck/vitess,vitessio/vitess,tinyspeck/vitess,vitessio/vitess,tinyspeck/vitess,vitessio/vitess,vitessio/vitess,vitessio/vitess,mahak/vitess,vitessio/vitess,tinyspeck/vitess,tinyspeck/vitess,mahak/vitess,mahak/vitess,mahak/vitess,mahak/vitess,mahak/vitess,tinyspeck/vitess,mahak/vitess,vitessio/vitess,tinyspeck/vitess,vitessio/vitess,mahak/vitess