[1808-2] cleanup: removed the NSEC4NXRRSET test.

it was once introduced in the 1808 branch, but it's not necessary now that
the generic findCheck() covers that case.

src/lib/datasrc/tests/memory_datasrc_unittest.cc

@@ -1049,17 +1049,6 @@ InMemoryZoneFinderTest::findCheck(ZoneFinder::FindResultFlags expected_flags,
              expected_nsec, expected_flags, NULL, find_options);
 }
 
-// Test if NSEC works
-TEST_F(InMemoryZoneFinderTest, NSEC4NXRRSET) {
-    findTest(origin_, RRType::TXT(), ZoneFinder::NXRRSET, true,
-             ConstRRsetPtr());
-
-    EXPECT_NO_THROW(EXPECT_EQ(SUCCESS, zone_finder_.add(rr_nsec_)));
-    findTest(origin_, RRType::A(), ZoneFinder::NXRRSET, true,
-             rr_nsec_, ZoneFinder::RESULT_NSEC_SIGNED, NULL,
-             ZoneFinder::FIND_DNSSEC);
-}
-
 TEST_F(InMemoryZoneFinderTest, find) {
     findCheck();
 }