Merge bitcoin/bitcoin#25027: test: Remove boost::split from getarg_tests.cpp

fafa727 test: Remove boost::split from getarg_tests.cpp (MacroFake)

Pull request description:

  Only single spaces are used, so no need for boost.

  Can be tested with:

  ```diff
  diff --git a/src/test/getarg_tests.cpp b/src/test/getarg_tests.cpp
  index c877105..a834830490 100644
  --- a/src/test/getarg_tests.cpp
  +++ b/src/test/getarg_tests.cpp
  @@ -21,8 +21,11 @@ BOOST_FIXTURE_TEST_SUITE(getarg_tests, BasicTestingSetup)
   void ResetArgs(ArgsManager& local_args, const std::string& strArg)
   {
       std::vector<std::string> vecArg;
  -    if (strArg.size())
  +    if (strArg.size()) {
           boost::split(vecArg, strArg, IsSpace, boost::token_compress_on);
  +        auto vecArg2{SplitString(strArg, ' ')};
  +        assert(vecArg2 == vecArg);
  +    }

       // Insert dummy executable name:
       vecArg.insert(vecArg.begin(), "testbitcoin");

ACKs for top commit:
  fanquake:
    utACK fafa727 - After this, the last usage of `<boost/algorithm/string.hpp>` is in `httprpc.cpp`.

Tree-SHA512: 038af095cfb5240216305919cdeeb12d8e3ff0424520b99785bff5353a47dfcacdc049b927d7316b13e17a3c19b5f7549c9db7c4b5f2fa78ff1816515ca28d9d

Author: fanquake

src/test/getarg_tests.cpp

@@ -13,16 +13,16 @@
 #include <utility>
 #include <vector>
 
-#include <boost/algorithm/string.hpp>
 #include <boost/test/unit_test.hpp>
 
 BOOST_FIXTURE_TEST_SUITE(getarg_tests, BasicTestingSetup)
 
 void ResetArgs(ArgsManager& local_args, const std::string& strArg)
 {
     std::vector<std::string> vecArg;
-    if (strArg.size())
-        boost::split(vecArg, strArg, IsSpace, boost::token_compress_on);
+    if (strArg.size()) {
+        vecArg = SplitString(strArg, ' ');
+    }
 
     // Insert dummy executable name:
     vecArg.insert(vecArg.begin(), "testbitcoin");