Reverts TF tests to use Keras 2 instead of 3

[EricLeFort]

Description

• Keras 3 breaks tests but this change reverts the tests to use Keras 2 instead

Tests

I ran on resnet v4-8 func. The test is still failing but it's clearing the Keras issue and making it further than it was previously.

Instruction and/or command lines to reproduce your tests:
./scripts/run-oneshot.sh -t tf.nightly-resnet-imagenet-func-v4-8-1vm

List links for your tests (use go/shortn-gen for any internal link):
http://shortn/_BFfQJMT0mS

Checklist

Before submitting this PR, please make sure (put X in square brackets):

• [ X ] I have performed a self-review of my code.
• [ X ] I have necessary comments in my code, particularly in hard-to-understand areas.
• [ X ] I have run one-shot tests and provided workload links above if applicable.
• [ X ] I have made or will make corresponding changes to the doc if needed.