Automatic merge from submit-queue (batch tested with PRs 63364, 63464). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

vsphere: use vim25.Client directly to support token authentication

**What this PR does / why we need it**:

This refactor is in support of SAML token authentication: #63209
Avoid use of govmomi.Client as it only supports username+password authentication via SessionManager.Login().
Using vim25.Client directly will allow VCP to add other authentication methods,
such as SessionManager.LoginByToken().

**Release note**:

```release-note
NONE
```