refactor: Replace !=/== tesSuccess with using isTesSuccess (#6409)

This change replaces all instances of `<variable> != tesSUCCESS` with `!isTesSuccess(<variable>)` and `<variable> == tesSUCCESS` with `isTesSuccess(<variable>)`.

src/test/app/FeeVote_test.cpp

@@ -114,7 +114,7 @@ bool
 applyFeeAndTestResult(jtx::Env& env, OpenView& view, STTx const& tx)
 {
     auto const res = apply(env.app(), view, tx, ApplyFlags::tapNONE, env.journal);
-    return res.ter == tesSUCCESS;
+    return isTesSuccess(res.ter);
 }
 
 bool