clangd only disabled once on machines with low memory

1. On a machine with less than 12GiB of memory, start Creator with empty settings.
   On the bottom of its window, Creator shows an info bar that the memory is not sufficient to use clangd.
2. Don't click the infobars at the bottom.
3. In "Edit" -> "Preferences..." -> "C++" -> "Clangd", verify that clangd is inactive.
4. Close Creator.
5. Start Creator with the same settings directory again.
   This time, there's no infobar about clangd.
6. In "Edit" -> "Preferences..." -> "C++" -> "Clangd", verify that clangd is inactive.
   Now it is active.

I think it makes sense that Creator disables clangd when there's not enough memory. It should remain disabled until the user explicitly enables it.