Remove HostMetadata and HostMetadataV6 protobuf messages, consolidate to HostMetadataV4V6

[Copilot]

Description

Consolidates three redundant host metadata protobuf message variants (HostMetadata, HostMetadataV6, HostMetadataV4V6) into a single HostMetadataV4V6 type that carries both IPv4 and IPv6 addresses along with AS number and labels.

Changes:

• Proto: Removed HostMetadataUpdate, HostMetadataRemove, HostMetadataV6Update, HostMetadataV6Remove messages from felixbackend.proto
• Calc layer: Removed separate IPv4/IPv6 callback interfaces (OnHostIPUpdate, OnHostIPRemove, OnHostIPv6Update, OnHostIPv6Remove) and pending state maps from EventSequencer; removed HostIPKey registration from DataplanePassthru
• Dataplane handlers: Updated noencap_mgr, wireguard_mgr, ipip_mgr, bpf_ep_mgr to handle only HostMetadataV4V6Update/HostMetadataV4V6Remove with IP version filtering
• External dataplane: Removed envelope wrapping for deleted message types

Components affected: felix/calc, felix/proto, felix/dataplane

Related issues/PRs

Todos

• Tests
• Documentation
• Release note

Release Note

Felix protobuf API consolidates HostMetadataUpdate/HostMetadataV6Update into HostMetadataV4V6Update. External dataplane drivers should update to handle the unified message type.

Reminder for the reviewer

Make sure that this PR has the correct labels and milestone set.

Every PR needs one docs-* label.

• docs-pr-required: This change requires a change to the documentation that has not been completed yet.
• docs-completed: This change has all necessary documentation completed.
• docs-not-required: This change has no user-facing impact and requires no docs.

Every PR needs one release-note-* label.

• release-note-required: This PR has user-facing changes. Most PRs should have this label.
• release-note-not-required: This PR has no user-facing changes.

Other optional labels:

• cherry-pick-candidate: This PR should be cherry-picked to an earlier release. For bug fixes only.
• needs-operator-pr: This PR is related to install and requires a corresponding change to the operator.

Original prompt

Felix protobuf messages includes 3 different HostMetadata variants. HostMetadata, HostMetadataV6, and HostMetadataV4V6. Remove HostMetadata and HostMetadataV6 and use HostMetadataV4V6 instead.

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.