* De-share the Handler struct in core API
An upcoming PR adds a handler that only applies on one of these paths.
Having fields that don't work seems bad.
This never should have been shared. Lifecycle hooks are like a "write"
while probes are more like a "read". HTTPGet and TCPSocket don't really
make sense as lifecycle hooks (but I can't take that back). When we add
gRPC, it is EXPLICITLY a health check (defined by gRPC) not an arbitrary
RPC - so a probe makes sense but a hook does not.
In the future I can also see adding lifecycle hooks that don't make
sense as probes. E.g. 'sleep' is a common lifecycle request. The only
option is `exec`, which requires having a sleep binary in your image.
* Run update scripts
We've changed the Ephemeral Containers API, and container type will no
longer be required. Since this is the only feature using it, remove it.
This reverts commit ba6f31a6c6.
This is part of the "Debug Containers" feature and is hidden behind
a feature gate. Debug containers have no stored spec, so this new
runtime label allows the kubelet to treat containers differently
without relying on spec.
