Change tone/ Expand needs a trailing space after tone in rewrite tools

[stephendonner]

Description

Change tone/ Expand needs a trailing space after tone in rewrite tools

Found while testing #37294

Steps to Reproduce

1. install 1.68.14
2. launch Brave
3. open a new-tab page
4. click on Leo in the sidebar
5. opt-in via I understand
6. type / in the input box
7. tab or scroll to the Change tone/ Expand option

Actual result:

Expected result:

Reproduces how often:

Brave version (brave://version info)

Brave | 1.68.14 Chromium: 125.0.6422.41 (Official Build) nightly (64-bit)
-- | --
Revision | b2b820a3f51cde3fbd10db0cb93be8a00642c5bb
OS | Windows 10 Version 22H2 (Build 19045.4412)

Version/Channel Information:

• Can you reproduce this issue with the current release?
• Can you reproduce this issue with the beta channel?
• Can you reproduce this issue with the nightly channel?

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information:

cc @nullhook @rebron @mattmcalister @brave/qa-team