Don't detach leaves on unload

[Zachatoo]

• detachLeavesOfType it's not recommended to detach leaves on unload. When updating your plugin, this means that all views will get discarded which might be annoying for users.

Originally posted by @liamcain in https://github.com/obsidianmd/obsidian-releases/pull/2097#issuecomment-1662454582