AEP-4016: remove mention of 'partial updates' in testing plan

[maxcao13]

What type of PR is this?

/kind documentation
/kind cleanup

What this PR does / why we need it:

Removes mention of "partial updates" from the AEP-4016 testing plan.

This is because, VPA accepts whole pods for updates if at least 1 container is considered "out of recommendation bounds", it doesn't care about which one(s). If at least one container is out of bounds, the updater will try to in-place resize the entire pod and update all containers with the most current recs. We shouldn't need to introduce new logic to apply resizes only to the containers that actually have recommendations out of bounds.

Which issue(s) this PR fixes:

Fixes #

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

- [AEP]: https://github.com/kubernetes/autoscaler/tree/master/vertical-pod-autoscaler/enhancements/4016-in-place-updates-support

[omerap12]

/lgtm

[raywainman]

/lgtm

/assign @voelzmo

[adrianmoisey]

/lgtm

[laoj2]

Can we still mention this point somewhere in this AEP? Maybe in "Details still to consider" section? So this doesn't get lost. It'll be great to implement partial updates at some point :)

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: maxcao13, omerap12
Once this PR has been reviewed and has the lgtm label, please ask for approval from raywainman. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• vertical-pod-autoscaler/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[adrianmoisey]

/lgtm

Good call out on retaining the info, rather than deleting it

[omerap12]

/lgtm