demote solana-vote-program to dev deps of solana-stake-program

[kevinheavey]

Problem

Following #4425, I realised solana-stake-program only needs solana-vote-program in dev deps

Summary of Changes

• Replace solana_vote_program with solana_program::vote where possible in solana-stake-program
• Move solana-vote-program to dev deps
• Remove superfluous metrics feature from solana-stake-program

[mergify]

The Firedancer team maintains a line-for-line reimplementation of the
native programs, and until native programs are moved to BPF, those
implementations must exactly match their Agave counterparts.
If this PR represents a change to a native program implementation (not
tests), please include a reviewer from the Firedancer team. And please
keep refactors to a minimum.