cross-region replication across versions produces log spam on leader

When Nomad regions are federated, the non-authoritative regions replicate various ACL-related objects such as namespaces, auth methods, and node pools. When the authoritative region is of a version that's older than the non-authoritative region, the non-authoritative region may request objects from RPCs that don't exist on the authoritative region. While mostly harmless, this produces a bunch of error log spam on the non-authoritative region's leader:

2023-07-20T11:59:15.945-0700 [ERROR] nomad: failed to fetch node pools from authoritative region: error="rpc error: rpc: can't find service NodePool.List"
2023-07-20T11:59:15.946-0700 [ERROR] nomad: failed to fetch ACL auth-methods from authoritative region: error="rpc error: rpc: can't find method ACL.ListAuthMethods"
2023-07-20T11:59:15.953-0700 [ERROR] nomad: failed to fetch ACL binding rules from authoritative region: error="rpc error: rpc: can't find method ACL.ListBindingRules"
2023-07-20T11:59:46.014-0700 [ERROR] nomad: failed to fetch node pools from authoritative region: error="rpc error: rpc: can't find service NodePool.List"
2023-07-20T11:59:46.015-0700 [ERROR] nomad: failed to fetch ACL auth-methods from authoritative region: error="rpc error: rpc: can't find method ACL.ListAuthMethods"
2023-07-20T11:59:46.022-0700 [ERROR] nomad: failed to fetch ACL binding rules from authoritative region: error="rpc error: rpc: can't find method ACL.ListBindingRules"
2023-07-20T12:00:16.083-0700 [ERROR] nomad: failed to fetch ACL auth-methods from authoritative region: error="rpc error: rpc: can't find method ACL.ListAuthMethods"
2023-07-20T12:00:16.084-0700 [ERROR] nomad: failed to fetch node pools from authoritative region: error="rpc error: rpc: can't find service NodePool.List"
2023-07-20T12:00:16.090-0700 [ERROR] nomad: failed to fetch ACL binding rules from authoritative region: error="rpc error: rpc: can't find method ACL.ListBindingRules"

It'd be nice if we could do version detection here, the same way we do for RPCs within a region, and then decide not to send these RPCs until the authoritative region is up-to-date as well.

Originally reported in https://github.com/hashicorp/nomad/issues/18007#issuecomment-1644445673

Trace the cross-region ACL and node-pool replication paths that emit the listed errors, then inspect how version detection is handled for intra-region RPCs. Done means unsupported RPCs are not sent to an older authoritative region, and the repeated error log spam is eliminated; the issue names no files or tests.