Cleanup End to End test framework

[shmuelk]

This PR cleans up the "framework" used by the end to end tests.

In particular it:

1. Deletes a duplicated load of the vLLM Simulator image
2. Deletes a forced Pull of the images needed from the code. This code is not needed for two reasons:
   1. The Makefile target test-e2e has a pre-requisite target of image-pull, which runs a scripts that verifies that the needed images are in the local directory.
   2. The code causes a pull of images from the remote repository even if an image with the appropriate tag exists locally.

[nirrozenbaum]

/lgtm
/approve

[nilig]

/lgtm
/approve