Delete unused JoinSplit crap from tests #191

After running ack -i joinsplit, there were a lot of results. I believe all this code is only used by sprout, so it needs to go.

Goal of this issue is to delete all joinsplittery from the following test files:

src/gtest/main.cpp
src/gtest/test_checkblock.cpp
src/gtest/test_checktransaction.cpp
src/gtest/test_mempool.cpp
src/gtest/test_transaction_builder.cpp
src/test/coins_tests.cpp
src/test/rpc_wallet_tests.cpp
src/test/sighash_tests.cpp
src/test/test_bitcoin.cpp
src/test/test_bitcoin.h
src/test/transaction_tests.cpp
src/wallet/gtest/test_transaction.cpp
src/wallet/gtest/test_wallet.cpp

@jahway603 welcome to the rabbit hole, it goes deep. Some of the remaining code related to JoinSplits can be removed (such as test code) but some of it is baked very deep into the internals and removing it would change how wallet.dat data is stored, making all wallets using the old code incompatible. Your mission, should you choose to accept it, is to decide what is what 😸

As an example of the power of ack, you can tell it to just tell us the files where a string matches, so these are all the test files which can be de-joinsplitted :

$ ack -l -i joinsplit src/ | grep test
src/gtest/main.cpp
src/gtest/test_checkblock.cpp
src/gtest/test_checktransaction.cpp
src/gtest/test_mempool.cpp
src/gtest/test_transaction_builder.cpp
src/test/coins_tests.cpp
src/test/rpc_wallet_tests.cpp
src/test/sighash_tests.cpp
src/test/test_bitcoin.cpp
src/test/test_bitcoin.h
src/test/transaction_tests.cpp
src/wallet/gtest/test_transaction.cpp
src/wallet/gtest/test_wallet.cpp

@jahway603 I made a checklist for each test file which has joinsplit junk, so you can focus on one file at a time if you want. Also, some files might contain only sprout stuff and nothing else, in that case, you can delete the whole file.