chore: cover multiple VRFs for unit test

[0xzrf]

Summary of Changes

• Describe what changed in the PR
  Updated render_peer_removal_successful in controlplane/controller/internal/controller/render_test.go to cover multi-VRF scenarios by switching UnicastVrfs from [1] → [1, 2] and assigning tunnels across VRFs (keeping tunnel 500 in VRF1; moving 501/502 to VRF2).
  Updated the golden fixture controlplane/controller/internal/controller/fixtures/unknown.peer.removal.tmpl to match the expected rendered output for multi-VRF peer removal (adds vrf2 routing/config sections, moves tunnel VRF assignments, and ensures unknown-peer no neighbor cleanup is rendered under each VRF).

• Explain why the change is necessary
  quoting from this issue:

  Today, this is only tested with one VRF. A regression in multi-VRF unknown peer removal would go undetected by the unit test suite. The existing multi.vrf.tunnel.tmpl fixture tests multi-VRF rendering but uses UnknownBgpPeers: nil, so it doesn't cover this case.

• Is there supporting documentation or external resources that explain the change? No

• Is a CHANGELOG.md update needed? No

Testing Verification

• Ran the focused unit subtest:

go test ./controlplane/controller/internal/controller -run '^TestRenderConfig$/render_peer_removal_successful$' -v

Closes #3633

[0xzrf]

hey @nikw9944

Can you review this PR?
Happy to make changes if needed
Thanks