change excluded extension state to 'not installed'

[cezaraugusto]

• Auditors: @bsclifton
• Close #8233

Test Plan:

1. Delete an extension
2. Extension should not disappear
3. Instead of trash icon you should see "not installed"

[bsclifton]

Moving to 0.14.3 😄 I discussed w/ @cezaraugusto, there is an outstanding issue where enabling (after excluding/removing) takes a while to reload the extension. Even restarting the browser doesn't always work