[single-pool-stake] Remove deprecated functions from cli

[samkim-crypto]

Problem

Solana clap-v3 utils deprecated a number of functions with version 1.18. #6278 temporarily suppresses the warnings from deprecated functions.

Solution

Remove the deprecated functions.

[tonton-sol]

Was going to work on this but it uses Clap Derive not Clap Builder. Is this intentional? Could I convert to builder, and if so should this be in a separate PR?

[samkim-crypto]

Thanks so much for the contribution! Clap derive is more readable and therefore, preferable over builder in general, so let's keep it derive for single-pool-stake. I have not checked yet if solana-clap-v3-utils currently has all the tools necessary to remove all the deprecated functions even for clap derive, but if not, then we can add the necessary interface to solana-clap-v3-utils.