agent: Remove unused Default implementation for NamespaceType

Currently we implement the Default trait for NamespaceType.  It doesn't
really make sense to have a default for this type though - you really need
to know what type of namespace you're setting.  In fact the Default
implementation is never used, so we can just drop it.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

src/agent/src/namespace.rs

@@ -178,12 +178,6 @@ impl fmt::Debug for NamespaceType {
     }
 }
 
-impl Default for NamespaceType {
-    fn default() -> Self {
-        NamespaceType::Ipc
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::{Namespace, NamespaceType};