remove support for legacy age categories

[macfarlandian]

Description of the change

Now that the new age categories are released and stable, we can remove our temporary support for the old ones in parallel with them (which was only in place for continuity while waiting for calc to start outputting the new data format).

Type of change

• Configuration change (adjusts configuration to achieve some end related to functionality, development, performance, or security)

Related issues

Closes #479

Checklists

Development

These boxes should be checked by the submitter prior to merging:

• Manual testing against realistic data has been performed locally

Code review

These boxes should be checked by reviewers prior to merging:

• This pull request has a descriptive title and information useful to a reviewer
• This pull request has been moved out of a Draft state, has no "Work In Progress" label, and has assigned reviewers
• Potential security implications or infrastructural changes have been considered, if relevant

[coveralls]

Pull Request Test Coverage Report for Build 1400948663

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 85.141%

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Files with Coverage Reduction	New Missed Lines	%
spotlight-client/src/metricsApi/types.ts	1	20.0%

Totals
Change from base Build 1400861097:	-0.1%
Covered Lines:	1986
Relevant Lines:	2211

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💛 - Coveralls