Disable test/box/admin_coredump.test.lua

coredump() feature is broken, see #1886

test/box/suite.ini

@@ -2,8 +2,7 @@
 core = tarantool
 description = Database tests
 script = box.lua
-disabled = rtree_errinj.test.lua tuple_bench.test.lua
-valgrind_disabled = admin_coredump.test.lua
+disabled = rtree_errinj.test.lua tuple_bench.test.lua admin_coredump.test.lua
 release_disabled = errinj.test.lua errinj_index.test.lua rtree_errinj.test.lua upsert_errinj.test.lua
 lua_libs = lua/fifo.lua lua/utils.lua lua/bitset.lua lua/index_random_test.lua lua/push.lua
 use_unix_sockets = True