Revert #120 "Add milestone age groups"

[lkeegan]

• resolves remove MilestoneAgeGroups #131

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 23.80952% with 16 lines in your changes missing coverage. Please review.

Project coverage is 23.76%. Comparing base (5fac037) to head (98a8bfa).

Files with missing lines	Patch %	Lines
frontend/src/lib/admin.svelte.ts	0.00%	5 Missing ⚠️
frontend/src/routes/admin/+page.svelte	0.00%	5 Missing ⚠️
...nd/src/lib/components/Admin/MilestoneGroups.svelte	0.00%	3 Missing ⚠️
frontend/src/routes/milestone/+page.svelte	0.00%	2 Missing ⚠️
frontend/src/lib/stores/adminStore.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #135      +/-   ##
==========================================
- Coverage   24.29%   23.76%   -0.54%     
==========================================
  Files          94       93       -1     
  Lines        3836     3707     -129     
  Branches      121      120       -1     
==========================================
- Hits          932      881      -51     
+ Misses       2836     2759      -77     
+ Partials       68       67       -1     

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[sonarqubecloud]

Quality Gate passed

Issues
6 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[MaHaWo]

lgtm