[Radarr][Change] Merge Movie and Downloads PVCs

[somerandow]

Special notes for your reviewer:

Related Issue: #222 Replace PVCs for movies and downloads with single 'media' PVC to resolve issues with hard-links on media import.

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• [x] Chart Version bumped
• [x] Variables are documented in the README.md
• [x] Title of the PR starts with chart name (e.g. [radarr])

[somerandow]

Realized I'd been removing the option for extraExistingClaims to be used. Retaining this functionality for those who choose to use it.