fix(kubevirt): migration disk serial

[yaroslavborbat]

Description

Fix disk serial handling for successful migration:

Previously, we set the disk serial to match the disk name, relying on Kubernetes to ensure the uniqueness of names. However, after this commit on QEMU, we can no longer do this, as QEMU no longer truncates the serial to 36 characters and now returns an error. We must handle the truncation ourselves. However, truncation does not guarantee uniqueness, so we switched to generating an MD5 hash of the disk name. The MD5 hash is easy to reproduce and fits the required 32-character length.

To ensure a successful migration, existing kvvm and kvvmi resources need to be patched to reflect the new serial format.

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

What is the expected result?

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: <kebab-case of a module name> | <1st level dir in the repo>
type: fix | feature | chore
summary: <ONE-LINE of what effectively changes for a user>