test(e2e): add precheck for affinity and toleration e2e

[LopatinDmitr]

Description

Add a dedicated e2e precheck for VirtualMachineAffinityAndToleration.

The test now declares its infrastructure dependency explicitly instead of using precheck.NoPrecheck.
The new precheck validates that the cluster has enough ready KVM-enabled nodes for the placement and migration scenarios covered by the test.

Why do we need it, and what problem does it solve?

VirtualMachineAffinityAndToleration depends on cluster topology:

• at least 2 ready KVM-enabled nodes;
• at least 1 ready KVM-enabled master node;
• at least 2 ready KVM-enabled worker nodes.

Before this change, the test used NoPrecheck, so these requirements were implicit and failures happened later during test execution.
With the new precheck, an unsuitable cluster is rejected during the precheck phase with a clear error message.

What is the expected result?

1. Run e2e with FOCUS=VirtualMachineAffinityAndToleration.
2. On a suitable cluster, the suite passes the precheck phase and proceeds to the test.
3. On an unsuitable cluster, the suite fails fast in SynchronizedBeforeSuite with a descriptive precheck error.

Checklist

• The code is covered by unit tests.
• e2e tests passed.
• Documentation updated according to the changes.
• Changes were tested in the Kubernetes cluster manually.

Changelog entries

section: test
type: chore
summary: Add a dedicated precheck for the VirtualMachineAffinityAndToleration e2e test.
impact_level: low