[Security Solution][Entity Analytics] Green execution of Cypress test…

…s on MKI (#179249)

## Summary

In this PR we are introducing several changes to make sure we have a
green execution of Cypress tests on MKI environments.

- Split `entity_analytics.cy.ts` between different spec files
- Skipped managed data section test on MKI
- Refactor of `installRiskScoreModule` method 


#### Split `entity_analytics.cy.ts` between different spec files

The original spec file has a big execution time, what makes from time to
time in MKI environment to perform a log off.

To try to avoid that, we have splited the spec file in 3 new ones inside
the `entity_analytics` folder.

* anomalies.cy.ts
* legacy_risk_score.cy.ts
* new_risk_score.cy.ts


#### Skipped managed data section test on MKI

It has been skipped just on MKI (the test will be executed in PRs for
both serverless and ESS) since I don't know how to fix it. A
[ticket](#179248) has been
created to track it. It is now responsability of the team to investigate
what is happening (I can give support with that).


#### Refactor of `installRiskScoreModule` method 

That method is returning a `401` on MKI, to fix it, we refactored to use
`rootRequest` instead since it uses the basic API authentication by
default.