Add VAP tests for PyTorchJobs

[ChristianZaccaria]

Jira: https://issues.redhat.com/browse/RHOAIENG-19694
ValidatingAdmissionPolicy PR: opendatahub-io/kueue#76

Note: this PR is on hold until the RFE is approved.

Description

• Added VAP tests for PyTorchJobs.
• Added new AppWrapper test cases.
• Refactored the tests for readability and scalability.

How Can This Been Tested?

This should be tested alongside this PR: opendatahub-io/kueue#76

Merge criteria:

• The commits are squashed in a cohesive manner and have meaningful messages.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work

[openshift-ci]

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