raft: concurrent limits on voting and recovery

[jcsp]

Cover letter

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Fixes #ISSUE-NUMBER, Fixes #ISSUE-NUMBER, ...

Backport Required

• [ ] not a bug fix
• [ ] papercut/not impactful enough to backport
• [ ] v22.2.x
• [ ] v22.1.x
• [ ] v21.11.x

UX changes

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Release notes