[1867904] Exec probes on VMI pods have various issues, let's remove them

Description of problem:

We use exec probes when we launch VMIs to know when virt-launcher is fully started.

We ran into the following issues with the exec probes:

https://bugzilla.redhat.com/show_bug.cgi?id=1817057
https://bugzilla.redhat.com/show_bug.cgi?id=1855067
https://bugzilla.redhat.com/show_bug.cgi?id=1848524
https://bugzilla.redhat.com/show_bug.cgi?id=1850168

Since it benefits kubevirt overall to just remove the exec probes, independent of seeing them fixed in OCP, I am proposing https://github.com/kubevirt/kubevirt/pull/3971, which is merged on master already.

This has the advantage that we don't rely on exec probes anymore (at the moment), removes exec probe warning events which we can't fully eliminate with the generic readiness mechanisms and speeds up VMI start.

I see this as the proper solution, because as one can see in https://bugzilla.redhat.com/show_bug.cgi?id=1855067 it may even require kernel setting changes to make exec probes work nicely with pod limits.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1.
2.
3.

Actual results:

Expected results:

Additional info: