Components: Do not render FormTokenField label when not defined

[retrofox]

What?

Changes introduced this PR doesn't not rendering the label elements when the property value is not defined

Why?

Because currently, the component renders element with empty content

How?

It will render the label components only when the property is defined

Testing Instructions

Using storybook

1. Run storybook locally

npm run storybook:dev

2. Select the default story for the TokenFormField component

http://localhost:50240/?path=/story/components-formtokenfield--default&args=label:

3. Confirm that when the label is empty or not defined, now the component does not add an additional empty space

before (trunk)	after (this PR)

4. You can confirm that currently (trunk) the component renders en empty label attribute

Testing Instructions for Keyboard

Screenshots or screencast

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: retrofox <retrofox@git.wordpress.org>
Co-authored-by: alexstine <alexstine@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[alexstine]

@retrofox Looks good. Do not forget to add a components changelog entry and then this is ready to merge given checks pass.

[retrofox]

@retrofox Looks good.

👍

Do not forget to add a components changelog entry and then this is ready to merge given checks pass.

I've added the entry, but the test still fails :-(

Please add a CHANGELOG entry to packages/components/CHANGELOG.md,
and make sure your CHANGELOG entry has a link to the current PR.

[github-actions]

Flaky tests detected in 64a42b4.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/8981159903
📝 Reported issues:

• [Flaky Test] Redirection after template creation #60678 in /test/e2e/specs/site-editor/site-editor-url-navigation.spec.js

[alexstine]

@retrofox Just pushed a commit, let's see if that makes them pass.

[retrofox]

Thanks 🙇‍♂️