[CI][SYCL][E2E] Remove igc-dev testing

[sarnex]

It causes much more trouble than the value is provides. The original idea was to get early feedback on JointMatrix changes, however I recently discussed this with Dounia and it seems we get basically zero value out of this anymore.

igc-dev testing relies on the IGC Github repo having passing CI and takes the CI artifacts.

The problems are:

1. The IGC GitHub CI build has been broken for months, so we can't update the driver used here, so now the non-igc-dev driver is actually newer than the igc-dev driver.
2. It uses GitHub CI artifacts directly, which expire, so we can't download the same version anymore after around a month, causing confusing CI fails (example here)
3. It requires complex handling in CI workflows, scripts, and E2E testing.

Just remove it.

[dkhaldi]

LGTM

[sarnex]

Merging now to fix confusing CI failures and prevent any new uses of igc-dev in tests once every is back since the main stakeholders already approved. The changes pending review are test changes and should be NFC for the remaining tests modes, but I am happy to address any feedback in a follow-up commit.