[Fleet]: Policies added to the integration aren't visible under Manage agent policies callout message.

[amolnater-qasource]

Kibana Build details:

VERSION: 8.15.0 BC3
BUILD: 76206
COMMIT: 674b3abcdff6f66d91d63a549e25218edce8b947

Preconditions:

1. 8.15.0-BC3 Kibana cloud environment should be available.
2. Integration should be added to multiple policies.

Steps to reproduce:

1. Navigate to Integrations>Integration policies tab.
2. Click on + icon under Agent policies and click Manage agent policies.
3. Remove 1 agent policy and observe the message is visible.
4. Add a new agent policy and observe the message in the callout doesn't show the added agent policy.

Expected Result:
Policies added to the integration should be visible under Manage agent policies callout message.

Similar message is available on editing the Integration:

Edit.integration.-.Agent.policy.4.-.Agent.policies.-.Fleet.-.Elastic.-.Google.Chrome.2024-07-24.12-20-40.mp4

Screen Recording:

Nginx.-.Integrations.-.Elastic.-.Google.Chrome.2024-07-24.12-06-20.mp4

Feature:
#75867

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[amolnater-qasource]

@karanbirsingh-qasource Please review.

[ghost]

secondary review for this ticket is Done

[juliaElastic]

This is actually intentional in Manage agent policies, the callout shows policies that are going to be removed, not policies that are going to be added. See in #182112