chore: Drop NetworkTopology::full_topology

[alin-at-dfinity]

NetworkTopology::full_topology (only populated for the NNS subnet) holds the same subnets as NetworkTopology::subnets and the same routing table as NetworkTopology::routing_table. Drop it altogether, as it is unused by all subnets but the NNS; and the NNS behaves identically with or without it (including in the case of a replica downgrade to a version that still populates it).

[zeropath-ai]

✅ No security or compliance issues detected. Reviewed everything up to 7d76ca5.

Security Overview

• 🔎 Scanned files: 14 changed file(s)
• 🔗 Scan Link: https://zeropath.com/app/repositories/f5e9d2bb-29a4-4b64-902a-391d65fd8b2d?scanId=efd39716-38bb-4219-becd-8743ad74f6a9&codeScanTypes=PrScan&tab=issues

Detected Code Changes

Change Type	Relevant files
Refactor	► rs/canonical_state/src/lazy_tree_conversion.rs     Replace usage of routing_table_for_certification() with routing_table(), and subnets_for_certification() with subnets() in multiple sites
Refactor	► rs/http_endpoints/nns_delegation_manager/src/nns_delegation_manager.rs     Use network_topology.routing_table() and network_topology.subnets() for delegation checks
Refactor	► rs/http_endpoints/nns_delegation_reader/src/reader.rs     Update documentation and references from routing_table_for_certification()/subnets_for_certification() to routing_table()/subnets()
Refactor	► rs/http_endpoints/public/tests/common/mod.rs     Adjust test expectations to align with routing_table() and subnets() usage
Refactor	► rs/messaging/src/message_routing.rs     Rename and adjust internal topology construction from full_topology/subnets_for_certification to standard subnets/routing_table (and related references)
Refactor	► rs/protobuf/def/state/metadata/v1/metadata.proto     Remove full_topology and related reserved field entries from NetworkTopology message
Refactor	► rs/protobuf/src/gen/state/state.metadata.v1.rs     Remove full_topology field from NetworkTopology struct
Refactor	► rs/replicated_state/src/metadata_state.rs     Remove FullTopology struct and full_topology field from NetworkTopology; adjust related comments and structure
Refactor	► rs/replicated_state/src/metadata_state/proto.rs     Remove serialization/deserialization handling for FullTopology in NetworkTopology
Refactor	► rs/replicated_state/src/metadata_state/tests.rs     Update tests to use routing_table() and subnets() and remove full_topology-related assertions

[schneiderstefan]

LGTM, but could you please do the RUN_ALL_BAZEL_TESTS thing, so that all upgrade downgrade tests have a chance to run?