server,rpc: the RPC heartbeat server incorrectly performs version check on CLI clients

[knz]

We have a cross-version compatibility guarantee between CLI clients and servers, such that it should be possible to use version N-1 of the CLI to access version N servers, and vice-versa.

There is a regression for this since v21.1 it is not any more possible to use e.g. a v21.2 CLI to operate a v22.1 server, or a v22.1 CLI to operate a v22.2 server.

(The problem still exists in v23.1)

For example, cockroach node drain fails with:

ERROR: failed to connect to the node: initial connection heartbeat failed: rpc error: code = Unknown desc = version compatibility check failed on ping request: cluster requires at least version 22.1-74, but peer has version 22.1

Jira issue: CRDB-20604

[blathers-crl]

Hi @knz, please add branch-* labels to identify which branch(es) this release-blocker affects.

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