Reduce lock-person icon size from 24px to 20px

This is a correction to the icon introduced in crrev.com/c/7385037.

Bug: 471021582
Change-Id: If35f652239bfb8bb71123724453592c9b48743ed
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/7499294
Commit-Queue: Paul Irish <[email protected]>
Reviewed-by: Danil Somsikov <[email protected]>
Reviewed-by: Paul Irish <[email protected]>

Author: thefrog-gh