fix: Remove unneeded import, fix log (#6532)

This change:
* Removes an unneeded import in `DeleteAccount.cpp`.
* Fixes a typo in a log statement in `SetAccount.cpp`.

src/libxrpl/tx/transactors/account/DeleteAccount.cpp

@@ -1,5 +1,4 @@
 #include <xrpl/basics/Log.h>
-#include <xrpl/basics/mulDiv.h>
 #include <xrpl/beast/utility/instrumentation.h>
 #include <xrpl/ledger/CredentialHelpers.h>
 #include <xrpl/ledger/View.h>

src/libxrpl/tx/transactors/account/SetAccount.cpp

@@ -491,7 +491,7 @@ SetAccount::doApply()
 
         if (messageKey.empty())
         {
-            JLOG(j_.debug()) << "set message key";
+            JLOG(j_.debug()) << "clear message key";
             sle->makeFieldAbsent(sfMessageKey);
         }
         else