[Hotfix] Always attest compute service regardless of what has been cached

[octaviansima]

This PR removes the check for cached attestation evidence in place of always retrieving it from the CS. The CS updates its own state when its asked for attestation evidence, and not initiating this call resulted in "Attestation not complete" error messages.

[chester-leung]

Can you please summarize the changes you made in the description?

Also, @ryanleh running mc2 stop should remove all cached attestation reports right? So I guess your change @octaviansima will have the client attest every time a mc2 run call is made?

[octaviansima]

I think the problem actually came from manually running/stopping the attestation service without using mc2 start or mc2 stop. When I would restart without stopping, then the GetRemoteEvidence would never be called and the CS would not begin attestation.

[chester-leung]

LGTM! Thanks!