scripted-diff: rename CChainState -> Chainstate

-BEGIN VERIFY SCRIPT-
sed -i 's/CChainState/Chainstate/g' $(git grep -l CChainState ':(exclude)doc/release-notes*')
-END VERIFY SCRIPT-

Co-authored-by: MacroFake <falke.marco@gmail.com>

src/test/net_tests.cpp

@@ -840,7 +840,7 @@ BOOST_AUTO_TEST_CASE(initial_advertise_from_version_message)
     const int64_t time{0};
     const CNetMsgMaker msg_maker{PROTOCOL_VERSION};
 
-    // Force CChainState::IsInitialBlockDownload() to return false.
+    // Force Chainstate::IsInitialBlockDownload() to return false.
     // Otherwise PushAddress() isn't called by PeerManager::ProcessMessage().
     TestChainState& chainstate =
         *static_cast<TestChainState*>(&m_node.chainman->ActiveChainstate());