A4A: fix referrals purchases count

[andrii-lysenko]

Resolves https://github.com/Automattic/jetpack-genesis/issues/375

Proposed Changes

Fix issue with wrong Purchases number in referrals overview. We were overwritting original. Also, refactored a function a bit.

Why are these changes being made?

Testing Instructions

• Using live link below make several referrals
• Navigate to /referrals/dashboard and check the number of referrals
• Leave the page and enter again, check that behavior is correct.

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
• For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-110567

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-110567&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-110567&env=a8c-for-agencies

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

Sections (~6 bytes added 📈 [gzipped])

name                        parsed_size           gzip_size
a8c-for-agencies-referrals        +22 B  (+0.0%)       +6 B  (+0.0%)

Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[yashwin]

Thanks for fixing this. LGTM.

I'm merging this one 💯