fix: [UIE-9733] - Optimize rendering of entities in AssignedRolesTable

[abailly-akamai]

Description 📝

This PR fixes a nasty rendering problem with the "Assigned Roles" and "Assigned Entities" User Detail pages.

When dealing with vert large entity data sets (> a few hundreds), the browser would start lagging (sometimes freezing in Safari) because of the data mounting/unmounting when entering/leaving the "Assigned Roles" tab.

The reason is, the computing is quite heavy for the TruncatedList component, which needs to make decisions on how to responsive show/hide the entity chips. When doing this with 1000 items it is a performance disaster. Good news is, we do not need to do that at all since we only need to show a small amount of items on the screen.

While this does not solve the initial loading of all entities (to be fixed later with better API support), this fix definitly prevents the browser issues we were seeing with large accounts

Changes 🔄

• Pass 15max items to Truncated list and update count button to still show the right number of hidden items based on the original data set

Scope 🚢

Upon production release, changes in this PR will be visible to:

• All customers
• Some customers (e.g. in Beta or Limited Availability)
• No customers / Not applicable

Target release date 🗓️

⚠️ 12/10/2025

How to test 🧪

Prerequisites

original reported bug in safari

v11.mov

Before	After
Screen.Recording.2025-12-05.at.15.05.27.mov	Screen.Recording.2025-12-05.at.15.04.28.mov

Testing

👉 A IAM account with large data sets

should be a restricted user with entities assigned

Reproduction steps

• navigate between /iam/users/<user>/roles and /iam/users/<user>/entities and refresh pages
• ⛔ notice UI lag (more so visible in Safari): after clicking the tab, the UI won't update for a couple seconds

Verification steps

• navigate between /iam/users/<user>/roles and /iam/users/<user>/entities and refresh pages
• ✅ notice no UI lag (we don't compute as much data)

Author Checklists

As an Author, to speed up the review process, I considered 🤔

👀 Doing a self review
❔ Our contribution guidelines
🤏 Splitting feature into small PRs
➕ Adding a changeset
🧪 Providing/improving test coverage
🔐 Removing all sensitive information from the code and PR description
🚩 Using a feature flag to protect the release
👣 Providing comprehensive reproduction steps
📑 Providing or updating our documentation
🕛 Scheduling a pair reviewing session
📱 Providing mobile support
♿ Providing accessibility support

• I have read and considered all applicable items listed above.

As an Author, before moving this PR from Draft to Open, I confirmed ✅

• All tests and CI checks are passing
• TypeScript compilation succeeded without errors
• Code passes all linting rules