This should be done before the branch-off, and can be done by anyone, as the steps are easily reproducible and reviewable.

#### Useful skills:

* Building Bitcoin Core
* Follow the documentation: https://github.com/bitcoin/bitcoin/blob/master/doc/release-process.md#before-branch-off

#### Want to work on this issue?

For guidance on contributing, please read [CONTRIBUTING.md](https://github.com/bitcoin/bitcoin/blob/master/CONTRIBUTING.md) before opening your pull request.

consensus.defaultAssumeValid = uint256{};
        pchMessageStart[0] = 0xfa;
        pchMessageStart[1] = 0xbf;
        pchMessageStart[2] = 0xb5;
        pchMessageStart[3] = 0xda;
        nDefaultPort = 18444;
        nPruneAfterHeight = args.GetBoolArg("-fastprune", false) ? 100 : 1000;
        m_assumed_blockchain_size = 0;
        m_assumed_chain_state_size = 0;
        UpdateActivationParametersFromArgs(args);
        genesis = CreateGenesisBlock(1296688602, 2, 0x207fffff, 1, 50 * COIN);
        consensus.hashGenesisBlock = genesis.GetHash();
        assert(consensus.hashGenesisBlock == uint256S("0x0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206"));
        assert(genesis.hashMerkleRoot == uint256S("0x4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b"));
        vFixedSeeds.clear(); 
        vSeeds.clear();
        vSeeds.emplace_back("dummySeed.invalid.");
        fDefaultConsistencyChecks = true;
        fRequireStandard = true;
        m_is_test_chain = true;
        m_is_mockable_chain = true;
        checkpointData = {
            {
                {0, uint256S("0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206")},
            }
        };
        m_assumeutxo_data = MapAssumeutxo{
            {
                110,
                {AssumeutxoHash{uint256S("0x1ebbf5850204c0bdb15bf030f47c7fe91d45c44c712697e4509ba67adb01c618")}, 110},