pkg/query: Scale merge profiles by period for diffing merges

[metalmatze]

• pkg/parcacol: Aggregate period and duration by timestamp
• pkg/query: Multiply the base and compare profiles for diffs

Something is still slightly off with the multiplication of values and diff values.

[alwaysmeticulous]

✅ Meticulous spotted zero visual differences across 391 screens tested: view results.

_{Last updated for commit d3861e5. This comment will update as new commits are pushed.}

[metalmatze]

There's still a memory leak I need to fix. We can probably remove the duration from the underlying ArrowDiffSchema again. It's not used. Some other clean-ups are left to do.