Update Deprecated waitForNextUpdate Hook to waitFor

[opauloh]

Motivation

The waitForNextUpdate hook in Testing Library is deprecated and will be removed in future versions. To ensure our tests remain compatible with upcoming versions and avoid potential failures, we need to replace instances of waitForNextUpdate with waitFor. This update will improve the maintainability and future-proofing of our test suite.

Fixing those will also help with the #195087, where some tests are falling due to the missing await.

Definition of done

• Identify all instances where waitForNextUpdate is used in the cloud_security_posture plugin's test code.
• - [ ] Identify all instances where waitForNextUpdate is used in the Agentless scope of fleet plugin's test code.
• Replace waitForNextUpdate with waitFor in each identified instance, ensuring that the tests still perform as expected.
• Validate that the updated tests pass and behave consistently with the original waitForNextUpdate implementation.
• Document any changes made and include notes on the new waitFor approach, if necessary.
• Submit a PR with these updates and notify relevant team members for review and feedback.

Out of scope

• Refactoring of unrelated tests or additional enhancements beyond updating waitForNextUpdate.
• Tests that are outside of the cloud_security_posture plugin or the Agentelss scope in the fleet plugin

Related tasks/epics

• Epic: Improving Test Automation Reliability for Cloud Risk Apps
• [React18] use waitFor with assertion callbacks in place of waitForNextUpdate #195087

[elasticmachine]

Pinging @elastic/kibana-cloud-security-posture (Team:Cloud Security)

[opauloh]

Closing as the changes are planned by this PR already implementing an ESLint rule to prevent further usage of waitForNextUpdate