[BUG] - Clearing a bookmark label text through the Toggle Labeled command leaves the leading spaces in the bookmark

[cateyes99]

Environment/version

• Extension version: 11.4.0
• VSCode version: 1.50.1
• OS version: Windows 10 Enterprise

Steps to reproduce
I saw #320 update in the latest release 11.4.0. So i gave a try. And found:

1. Add a new bookmark on a line which has leading spaces, i.e., the below one has some spaces at the beginning before some text ...
   
2. In the BOOKMARKS: EXPLORER, it looks like. All good.
   
3. Add a bookmark label, say aaa, to the bookmark.
4. Now through the Toggle Labeled command from VSCode's Command Palette, clear the text aaa in the input box. Then found the bookmark on the BOOKMARKS: EXPLORER looks like this:
   

Note: If i clear the bookmark label through the Edit Label from the BOOKMARKS: EXPLORER instead, as a result the bookmark in BOOKMARKS: EXPLORER will look normal as in 2, unlike in 4.

Interestingly, I tested the behaviours in the previous versions up to 11.0.0. Turn out that those old versions they've already support clearing bookmark label through the Edit Label from the BOOKMARKS: EXPLORER.

Furthermore, version 11.0.0 not just supports this through the Edit Label but also supports it through the Toggle Labeled command from VSCode's Command Palette already and doesn't have this bug 👀 .