test: Remove unused fCheckpointsEnabled from miner_tests

The earliest checkpoint is at height 11111, so this can't possibly have
any impact on this test.

Author: MacroFake

src/test/miner_tests.cpp

@@ -558,8 +558,6 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
     CScript scriptPubKey = CScript() << ParseHex("04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5f") << OP_CHECKSIG;
     std::unique_ptr<CBlockTemplate> pblocktemplate;
 
-    fCheckpointsEnabled = false;
-
     // Simple block creation, nothing special yet:
     BOOST_CHECK(pblocktemplate = AssemblerForTest(chainparams).CreateNewBlock(scriptPubKey));
 
@@ -608,8 +606,6 @@ BOOST_AUTO_TEST_CASE(CreateNewBlock_validity)
     m_node.mempool->clear();
 
     TestPrioritisedMining(chainparams, scriptPubKey, txFirst);
-
-    fCheckpointsEnabled = true;
 }
 
 BOOST_AUTO_TEST_SUITE_END()