Don't unshare after entering global namespace (#2373)

Global namespace is usually used to publicly apply mounts so calling
unshare after entering root namespace is not desired bahavior. This also
keeps -M option same as Magisk.

userspace/ksud/src/cli.rs

@@ -305,7 +305,6 @@ pub fn run() -> Result<()> {
             #[cfg(any(target_os = "linux", target_os = "android"))]
             {
                 utils::switch_mnt_ns(1)?;
-                utils::unshare_mnt_ns()?;
             }
             match command {
                 Module::Install { zip } => module::install_module(&zip),