[Task] Migrate the Apollo registry, data-sync, admin-listener, and starters to shenyu-plugin-store #7599

Background

Apache ShenYu is executing a phased migration of optional integrations out of the
main repository and into the external extension repository
apache/shenyu-plugin-store (tracked
by #7306). Consul is the reference precedent (#7308), with Eureka (#7596) and etcd
(#7597) following the same pattern.

The registry layer was decoupled in #7578: every registry now implements the
ShenyuInstanceRegisterRepository SPI and is loaded via
ShenyuInstanceRegisterRepositoryFactory.loadRepository, so it can be cleanly
externalized without touching the gateway core. Apollo already follows this pattern
(ApolloInstanceRegisterRepository + RegistrySpiTest), which makes it a good
candidate for the same move.

Note: unlike Consul (already marked external), Apollo is still a first-class,
supported backend — the README lists it alongside Nacos/etcd as an available
sync mechanism ("HTTP long polling, ZooKeeper, Nacos, etcd, and Apollo are
available"). Therefore externalizing it requires a dev-list consensus + deprecation
cycle, exactly as etcd (#7597). Apollo is also not part of the original #7306
child set (#7294–#7308), so this issue extends the plan rather than completing it.

Scope

Remove / move out of apache/shenyu

• shenyu-registry/shenyu-registry-apollo (registry implementation; implements ShenyuInstanceRegisterRepository)
• shenyu-sync-data-center/shenyu-sync-data-apollo (data-sync backend; ApolloDataService, ApolloConfig)
• shenyu-admin-listener/shenyu-admin-listener-apollo (ApolloSyncConfiguration)
• shenyu-spring-boot-starter/shenyu-spring-boot-starter-sync-data-center/shenyu-spring-boot-starter-sync-data-apollo
• shenyu-common/.../constant/ApolloPathConstants.java (evaluate — may be shared; move or keep minimal shim)
• README.md line "and Apollo are available" → update to "external extension (see plugin-store-apollo.md)"

Add to apache/shenyu-plugin-store

Mirror the Consul structure (docs/plugin-store-consul.md):

• shenyu-registry-apollo + shenyu-sync-data-apollo + shenyu-admin-listener-apollo + starters
• docs/plugin-store-apollo.md documenting install/enable + cutover contract

Acceptance Criteria

• All Apollo artifacts build and pass tests inside shenyu-plugin-store.
• ShenyuInstanceRegisterRepositoryFactory.loadRepository still resolves Apollo when the plugin-store jar is on the classpath (no core change).
• docs/plugin-store-apollo.md published with install + enable steps and the [Task] Track the phased migration of optional integrations to shenyu-plugin-store #7306 cutover contract.
• README updated; deprecation note + migration guide added for one release before removal from core.
• CI: main-repo build no longer compiles Apollo; plugin-store CI covers it.

Related

• [Task] Track the phased migration of optional integrations to shenyu-plugin-store #7306 (umbrella) · [Task] Migrate the Consul data-sync and registry integration to shenyu-plugin-store #7308 (Consul, precedent) · [Task] Migrate the Eureka registry integration to shenyu-plugin-store #7596 (Eureka) · [Task] Migrate the etcd registry and data-sync integration to shenyu-plugin-store #7597 (etcd)
• [ISSUE #7311] Decouple registry core from implementations. #7578 (registry SPI decoupling that enables this)