remove unused viz series utils

[EmmadUsmani]

Description

Removing some viz related code that is no longer used post-echarts migration.

How to verify

1. New question -> Orders count by month
2. Confirm chart renders

Demo

Checklist

• [x] Tests have been added/updated to cover changes in this PR

[EmmadUsmani]

• #42422 👈
• master

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[github-actions[bot]]

Codenotify: Notifying subscribers in CODENOTIFY files for diff 1f416069d0c70c406b1fac195f116d2f82a5596d...3f82cba04242845fb12d1eed7428fa9b9842fdd7.

Notify	File(s)
@alxnddr	frontend/src/metabase/visualizations/lib/series.ts frontend/src/metabase/visualizations/lib/series.unit.spec.ts

[replay-io[bot]]

Status	Complete ↗︎
Commit	3f82cba04242845fb12d1eed7428fa9b9842fdd7
Results	⚠️ 6 Flaky ✅ 2475 Passed

[github-actions[bot]]

@EmmadUsmani Did you forget to add a milestone to the issue for this PR? When and where should I add a milestone?