Merge #20067: refactor: remove use of boost::algorithm::replace_first

6f4e393 refactor: remove use of boost::algorithm::replace_first (Sebastian Falbesoner)

Pull request description:

  As discussed in #19851 (bitcoin/bitcoin#19851 (comment)), this trivial PR substitutes the (only) use of `boost::algorithm::replace_first` by a direct implementation.

ACKs for top commit:
  laanwj:
    Code review ACK 6f4e393

Tree-SHA512: 2ef06498e19f864a4cbae10e8d1905e3440a2d1e8e5aae83de7597c23cdab92b4612d7fa1efbc49016e530debd127d1d50531c60ff159dbea0deaa8c836a2bfb

Author: laanwj

src/core_read.cpp

@@ -15,7 +15,6 @@
 #include <version.h>
 
 #include <boost/algorithm/string/classification.hpp>
-#include <boost/algorithm/string/replace.hpp>
 #include <boost/algorithm/string/split.hpp>
 
 #include <algorithm>
@@ -40,8 +39,9 @@ CScript ParseScript(const std::string& s)
                 continue;
             mapOpNames[strName] = static_cast<opcodetype>(op);
             // Convenience: OP_ADD and just ADD are both recognized:
-            boost::algorithm::replace_first(strName, "OP_", "");
-            mapOpNames[strName] = static_cast<opcodetype>(op);
+            if (strName.compare(0, 3, "OP_") == 0) {  // strName starts with "OP_"
+                mapOpNames[strName.substr(3)] = static_cast<opcodetype>(op);
+            }
         }
     }