Fixed the problem that creating template item results in page which never finishes loading

[kunovercammen]

References

• Fixes Creating Template Item results in a page which never finishes loading #2938

Description

Updated the retrieveDataService() method to address an issue where the Template Item page for creating a new Item Template for a Collection fails to load. The method now correctly returns the updateDataService when available instead of returning empty.

Instructions for Reviewers

List of changes in this PR:

• Updated the retrieveDataService() method to return the updateDataService when available instead of returning empty, resolving the issue with the non-loading Template Item page.
• Added e2e test to verify the display of specific elements on the item template page.

How to test:

1. Edit a Collection.
2. Click "+Add" under Template Item.
3. Verify that the page successfully loads without any indefinite loading.
4. Perform additional actions such as canceling, editing, or deleting the Template Item to ensure consistent behavior.

Checklist

• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• My PR passes ESLint validation using yarn lint
• My PR doesn't introduce circular dependencies (verified via yarn check-circ-deps)
• My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• If my PR includes new libraries/dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.
• If my PR includes new features or configurations, I've provided basic technical documentation in the PR itself.
• If my PR fixes an issue ticket, I've linked them together.

[tdonohue]

👍 Thanks @kunovercammen ! This fixes the bug. I also appreciate it that you've added an e2e test for this feature to ensure it isn't broken in the future.