fix(core, kubevirt): add ability to configure burst for virt-api rate limiter

[Isteb4k]

Description

When migrating a big number of virtual machines (>50), we encounter a bottleneck in virt-api in the form of a rate limiter that prevents migration completion.

A patch has been updated to virt-api, enabling the configuration of Burst for the rate limiter via an environment variable VIRT_API_RATE_LIMITER_BURST.

Checklist

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