Make the E2E supporting VKS data mover environment.

[blackpiglet]

• Add new flag DISABLE_VSPHERE_PLUGIN for E2E test.
• Modify the E2E README for the new parameter.
• Add the VolumeSnapshotClass for VKS.
• Modify the plugin install logic.
• Modify the E2E to support data mover cases in VKS.

Thank you for contributing to Velero!

Please add a summary of your change

Does your change fix a particular issue?

Fixes #(issue)

Please indicate you've done the following:

• [x] Accepted the DCO. Commits without the DCO will delay acceptance.
• [ ] Created a changelog file (make new-changelog) or comment /kind changelog-not-required on this PR.
• [ ] Updated the corresponding documentation in site/content/docs/main.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 58.95%. Comparing base (db470a7) to head (bebea4d). Report is 28 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #8371 +/- ## ========================================== - Coverage 58.95% 58.95% -0.01% ========================================== Files 367 367 Lines 38876 38902 +26 ========================================== + Hits 22920 22933 +13 - Misses 14493 14507 +14 + Partials 1463 1462 -1 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.