refactor: Rename non-functional uses of ripple(d) to xrpl(d) (#6676)

Co-authored-by: Bart <11445373+bthomee@users.noreply.github.com>

src/test/jtx/impl/Oracle.cpp

@@ -18,7 +18,7 @@ Oracle::Oracle(Env& env, CreateArg const& arg, bool submit) : env_(env)
     // {close-maxLastUpdateTimeDelta, close+maxLastUpdateTimeDelta}.
     // To make the validation work and to make the clock consistent
     // for tests running at different time, simulate Unix time starting
-    // on testStartTime since Ripple epoch.
+    // on testStartTime since XRPL epoch.
     auto const now = env_.timeKeeper().now();
     if (now.time_since_epoch().count() == 0 || arg.close)
         env_.close(now + testStartTime - epoch_offset);