Fix mobile artist badge centering

[raymondjacobson]

Summary

• Center the actual rendered mobile artist row, including badges, by removing the hidden badge spacer row
• Keep badges next to each artist name in multi-artist rows
• Add a test guard so each artist badge set only renders once

Verification

• npm run typecheck -w @audius/mobile -- --noEmit
• npm run lint -w @audius/mobile -- src/components/user-link/TrackArtists.tsx src/components/user-link/TrackArtists.test.tsx src/screens/track-screen/TrackScreenDetailsTile.tsx
• cd packages/mobile && ../../node_modules/.bin/jest src/components/user-link/TrackArtists.test.tsx --runInBand

[changeset-bot]

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Latest commit: 88389ec

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