Merge bitcoin/bitcoin#25025: test: Remove boost::split from rpc_tests.cpp

fad35e9 test: Remove boost::split from rpc_tests.cpp (MacroFake)

Pull request description:

  No need for boost, as there are no tabs.

  Can be tested with:

  ```diff
  diff --git a/src/test/rpc_tests.cpp b/src/test/rpc_tests.cpp
  index 50b5078..ad6a888ad0 100644
  --- a/src/test/rpc_tests.cpp
  +++ b/src/test/rpc_tests.cpp
  @@ -29,6 +29,7 @@ public:

   UniValue RPCTestingSetup::CallRPC(std::string args)
   {
  +Assert(args.find('\t')==std::string::npos);
       std::vector<std::string> vArgs;
       boost::split(vArgs, args, boost::is_any_of(" \t"));
       std::string strMethod = vArgs[0];

ACKs for top commit:
  fanquake:
    utACK fad35e9

Tree-SHA512: 3df789a222b407d61ad549adc4bbded00705d7c3db07472c31ce0e82216fe3ae27724b7f0ee3e85084bdf405cc28185e85487c9a7001620d6654fda77bab8eb3

Author: MacroFake

src/test/rpc_tests.cpp

@@ -2,25 +2,21 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include <rpc/client.h>
-#include <rpc/server.h>
-#include <rpc/util.h>
-
 #include <core_io.h>
 #include <interfaces/chain.h>
 #include <node/context.h>
+#include <rpc/blockchain.h>
+#include <rpc/client.h>
+#include <rpc/server.h>
+#include <rpc/util.h>
 #include <test/util/setup_common.h>
+#include <univalue.h>
 #include <util/time.h>
 
 #include <any>
 
-#include <boost/algorithm/string.hpp>
 #include <boost/test/unit_test.hpp>
 
-#include <univalue.h>
-
-#include <rpc/blockchain.h>
-
 class RPCTestingSetup : public TestingSetup
 {
 public:
@@ -29,8 +25,7 @@ class RPCTestingSetup : public TestingSetup
 
 UniValue RPCTestingSetup::CallRPC(std::string args)
 {
-    std::vector<std::string> vArgs;
-    boost::split(vArgs, args, boost::is_any_of(" \t"));
+    std::vector<std::string> vArgs{SplitString(args, ' ')};
     std::string strMethod = vArgs[0];
     vArgs.erase(vArgs.begin());
     JSONRPCRequest request;