[dnssec] tests: remove separate tests for pubkey

The interface is already tested as a part of 'key' tests. It makes no
sense to tests this separately (at the moment).

dnssec/tests/Makefile.am

@@ -13,7 +13,6 @@ check_PROGRAMS = \
 	key		\
 	key_keyid	\
 	key_keytag	\
-	key_pubkey	\
 	nsec_bitmap	\
 	nsec_hash	\
 	random		\

dnssec/tests/key_pubkey.c

-#include <tap/basic.h>
-
-int main(void)
-{
-	plan_lazy();
-
-	return 0;
-}