Document Tree - Performance Issues when Expanding All Files

**Describe the bug in current situation**
A clear and concise description of what the bug is.

In the Redaction App, when expanding all files in the package (i.e., to show all the pages) in the left pane / document tree, performance is significantly impacted on larger requests.

For example, on FOR-2023-30509, which contains 286 files, when selecting to expand all in the left pane / document tree, performance is impacted when trying to perform further actions in the left pane / document tree.

Selecting pages, apply page flags, expanding or collapsing files all take seconds to respond.

This ticket is to investigate performance related challenges/improvements related to this feature.

**Link bug to the User Story**

#4432

**Impact of this bug**
Describe the impact, i.e. what the impact is, and number of users impacted.

Low

**Chance of Occurring (high/medium/low/very low)**

Medium

**Pre Conditions: which Env, any pre-requesites or assumptions to execute steps?**

PROD and TEST

**Steps to Reproduce**
Steps to reproduce the behavior:
1. Go to FOR-2023-30509 in the Redaction App
2. Expand all files in the left pane / document tree
3. Click a page in the package, or right click to bring up the page flag context menu
4. See performance issues

**Actual/ observed behaviour/ results**

Performance impacted when expanding all files

**Expected behaviour**
A clear and concise description of what you expected to happen. Use the gherking language.

**Screenshots/ Visual Reference/ Source**
If applicable, add screenshots to help explain your problem. You an use screengrab.

Start by reproducing the issue in the Redaction App's left-pane document tree using FOR-2023-30509: expand all files, then select a page, apply page flags, and expand or collapse files. Trace the document-tree entry point and measure the slow actions before and after investigation; done means those actions remain responsive for large requests.

Written by the indexing model from the issue text.