Walk Failing on Demux Snapshotter after Garbage Collection

[ginglis13]

Walk fails on task exit after garbage collection when using the demux snapshotter with error:

time="2022-05-26T17:37:20Z" level=error msg="Function called without namespaced context" error="namespace is required: failed precondition" function=Walk

This shows up in demux snapshotter logs; not seeing a related error in firecracker-containerd logs but we should root cause this.

[austinvazquez]

I feel like this may not be the entire solution. Reran integration tests with the above fix and am now seeing the following logs.

time="2022-06-01T18:04:26Z" level=error msg="Function called without namespaced context" error="namespace is required: failed precondition" function=Walk
time="2022-06-01T18:04:26Z" level=debug msg="no namespace found, proxying walk function to all cached snapshotters" function=Walk
time="2022-06-01T18:04:26Z" level=error msg="Function called without namespaced context" error="namespace is required: failed precondition" function=Remove
time="2022-06-01T18:04:26Z" level=error msg="Function called without namespaced context" error="namespace is required: failed precondition" function=Remove

Garbage collection is unable to provide namespace for Remove requests. Should we consider broadcasting these as well if no namespace is provided?

@Kern-- @ginglis13

[austinvazquez]

@ginglis13, I have opened #678 which addresses garbage collection using in-VM snapshotter. Please have a look and provide feedback.