[FTR][Tech Debt] Too many alerting api helpers, can they be reduced?

[wayneseymour]

Summary

Recently the topic of how we have 15 calls to /api/alerting/rule within x-pack/test/api_integration/deployment_agnostic/services/alerting_api.ts and perhaps other duplications.

Github PR comments discussing this problem.

• The ask for documentation on this is within the comment

Really this code just needs a good "scrub down" and hopefully we can get the footprint much smaller through zero duplication

Some background

We've already begun this work with this PR here & here chronologically.

[elasticmachine]

Pinging @elastic/appex-qa (Team:QA)