test: quote focus/label args in e2e precheck prepare

[yaroslavborbat]

Description

Fix test/e2e precheck prepare scripts: pass FOCUS/LABELS to ginkgo with proper quoting (values may contain spaces).

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

When FOCUS contains spaces, precheck:prepare could fail to generate /tmp/e2e-specs.json, causing SynchronizedBeforeSuite to fail early.

What is the expected result?

Focused e2e runs with FOCUS containing spaces complete precheck preparation and do not fail due to missing /tmp/e2e-specs.json.

Steps:

• FOCUS='when changes are applied manually' task -d test/e2e precheck:prepare
• FOCUS='when changes are applied manually' task -d test/e2e run

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: fix
summary: "Fix e2e precheck prepare for focus/label filters containing spaces."
impact_level: low