CRM: Remove legacy code

[tbradsha]

This PR removes lots of legacy (e.g. pre-DAL3) code.

Other information:

• [ ] Have you written new tests for your changes, if applicable?
• [ ] Have you checked the E2E test CI results, and verified that your changes do not break them?
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Jetpack product discussion

Does this pull request change what data or activity we track or use?

Testing instructions:

Verify site click-through is working.

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