The gVisor shim is registere as containerd TTRPC plugin.
The change removes global `id` filed from runsc task service, which transitions
the shim from a single container per shim assumption to multi continers per
shim architecture.
This CL modernizes the gVisor `runsc` shim by transitioning from the legacy
`containerdshim.Run` to the modern `containerdshim.RunManager` bootstrap flow.
Since the containerdshim.Run is removed in containerd 2.0 and later, it allows
us to migrate gVisor to integrate with containerd 2.0+.
This aligns the `runsc` shim with the `runc` architecture and allows it to be
loaded natively as a containerd plugin.
PiperOrigin-RevId: 912797962
