I'm not so sure this issue is at all addressed. I saw this issue because I am currently receiving a notification that I cannot dismiss for the "WMI Windows Agent Plugin" (aka "windows-slaves") being deprecated in version 2.378. I tried to uninstall it... and it looks like I can, because it doesn't look like anything is depending on it. It is currently disabled, and no plugins are complaining, anyway. When I mark it deleted, it says "uninstallation pending". However, when I restart, it always comes back as though I never tried to uninstall it.
In short, I cannot dismiss the deprecation message and I cannot uninstall it. It does not appear to be needed... I'm running on a single node Jenkins on Linux and have no need of it. But I can't get rid of it.
This plugin was detached from the core in 2013, and many old plugins implicitly depend on it (Jenkins assumes they might need something from a detached plugin).