fix(GODT-3054): Delete draft create from reply

If an IMAP client creates a new message as a reply/forward from an
existing draft, that draft will be deleted once the message has been
sent.

Other than not being the correct behavior, the original reason for which
this line of code was added (carried over from v2), seems to be no longer
necessary as in all tests, the message is correctly removed from the
drafts folder after sent.

internal/services/smtp/smtp.go

@@ -292,8 +292,6 @@ func getParentID(
 		for _, metadata := range metadata {
 			if !metadata.IsDraft() {
 				parentID = metadata.ID
-			} else if err := client.DeleteMessage(ctx, metadata.ID); err != nil {
-				return "", fmt.Errorf("failed to delete message: %w", err)
 			}
 		}
 	}