What this PR does / why we need it:

The registry_proto_cache decorators in proto_registry_utils keyed on id(registry_proto) as well as version_id. A registry refresh parses a new proto object, so every refresh missed the cache and rebuilt every object from proto even when the registry had not changed. With 14 feature services that rebuild is about 35 ms per refresh, most of it typeguard checks in Field.__init__. Measured locally with a file registry, refresh plus list_feature_services(allow_cache=True):

Changes:

• Key the three cache decorators on version_id alone. A registry without a version_id falls back to object identity, which is today's behavior.
• Cache get_feature_service per version with the existing registry_proto_cache_name decorator. get_online_features calls it on every request and it rebuilt the FeatureService from proto each time, about 2 ms per call.
• Stamp SqlRegistry.proto() and SnowflakeRegistry.proto() with a version_id. Neither set one, so for those registries the caches would have kept falling back to object identity and missing on every refresh. The value is the sha1 of the deterministic serialization, stable across refreshes and different after any apply or delete. On a 421 KB proto the hash costs 0.2 ms. The file, S3, GCS, Azure, and HDFS stores already stamp a uuid on each write.

Profiled effect on get_online_features with a file registry, 100 entities, 4 feature views: a warm read has no from_proto or typeguard frames left on the registry side. The first read after a refresh costs 14.2 ms against 19.6 ms with the old object-identity key, and the same 5 ms saving now applies to SQL-registry deployments once per cache refresh.

No behavior change for callers. Cached objects were already shared between calls on the same proto object.

Which issue(s) this PR fixes:

Refs #7072 (proposal 3)

Checks

• I've made sure the tests are passing.
• My commits are signed off (git commit -s)
• My PR title follows conventional commits format

Testing Strategy

• Unit tests
• Integration tests
• Manual tests
• Testing is not required for this change

Unit tests cover a re-parsed proto with the same version_id hitting the cache, a new version_id missing it, registries without a version_id staying per-object, get_feature_service returning the cached object, and a SQL registry whose version_id is stable across proto() calls and refreshes and changes after an apply. sdk/python/tests/unit/infra/registry passes locally (164 tests; three modules skip collection for missing optional dependencies).