Disabling Status Bar Color Control doesn't delete status bar color configuration

Describe the bug
Disabling the Status Bar Color Control option doesn't remove the color configuration in settings, leaving the status bar "stuck" in the last color mode it was on when disabled. User needs to manually delete the relevant workbench.colorCustomizations settings in settings.json to reset the status bar to its theme color.

To Reproduce
Steps to reproduce the behavior:

1. Go to Settings
2. Enable Status Bar Color Control
3. In an editor, change the vim mode (e.g. press I to enter insert mode)
4. See the status bar color change
5. In Settings, disable Status Bar Color Control
6. In the editor, see the status bar remain the previous color
7. In settings.json, see the workbench.colorCustomizations entry with the previous value

Expected behavior
The status bar color should be reset by deleting the workbench.colorCustomizations entry in settings.json.

Screenshots

Environment (please complete the following information):

• Extension (VsCodeVim) version: 1.18.5
• VSCode version: 1.52.1
• OS: macOS Big Sur 11.1

Start by reproducing the Status Bar Color Control flow and inspect the code that writes the workbench.colorCustomizations entry to settings.json. Trace what happens when the option is disabled, then verify that the previous status bar color configuration is removed and the status bar returns to its theme color.