all: don't repeat the the word "the" unnecessarily

Updates #cleanup

Change-Id: Ic1f430cd5dbf6cc1a385c59074a5d5cabe6fca57
Signed-off-by: Alex Chan <alexc@tailscale.com>

util/winutil/winutil_windows.go

@@ -577,7 +577,7 @@ func lookupPseudoUser(uid string) (*user.User, error) {
 	}
 
 	// We're looking for SIDs "S-1-5-x" where 17 <= x <= 20.
-	// This is checking for the the "5"
+	// This is checking for the "5"
 	if sid.IdentifierAuthority() != windows.SECURITY_NT_AUTHORITY {
 		return nil, fmt.Errorf(`SID %q does not use "NT AUTHORITY"`, uid)
 	}