Replace custom replace utility with the stdlib's replace algorithm.

This removes the custom `replaceAll` function, replacing it with
`std::replace` from the stdlib's `<algorithm>` header.

This also removes the respective unit test.

More importantly, this removes the dependency on the
`<boost/algorithm/string.hpp>` header in the `string_util.hpp` header.

util/string_util.hpp

@@ -28,8 +28,6 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #ifndef STRING_UTIL_HPP
 #define STRING_UTIL_HPP
 
-#include <boost/algorithm/string.hpp>
-
 #include <cctype>
 
 #include <random>
@@ -83,11 +81,6 @@ template <int length, int precision> static inline char *printInt(char *buffer,
     return buffer;
 }
 
-inline void replaceAll(std::string &s, const std::string &sub, const std::string &other)
-{
-    boost::replace_all(s, sub, other);
-}
-
 inline std::string escape_JSON(const std::string &input)
 {
     // escape and skip reallocations if possible