Review feedback from @yinyiqian1

- Rewrite to_short_string to call strHex directly instead of building
  the whole hex string first.
- Change PrettyAsset::scale_ back to a uint32 since the Number
  conversion elides any potential multiplication overflow.
- Clean ups.

include/xrpl/basics/base_uint.h

@@ -636,7 +636,12 @@ template <std::size_t Bits, class Tag>
 inline std::string
 to_short_string(base_uint<Bits, Tag> const& a)
 {
-    return to_string(a).substr(0, 8) + "...";
+    // LCOV_EXCL_START
+    if constexpr (a.bytes <= 4)
+        return to_string(a);
+    else
+        // LCOV_EXCL_STOP
+        return strHex(a.cbegin(), a.cbegin() + 4) + "...";
 }
 
 template <std::size_t Bits, class Tag>

src/test/jtx/TestHelpers.h

@@ -361,7 +361,7 @@ ownerCount(test::jtx::Env const& env, test::jtx::Account const& account);
 
 [[nodiscard]]
 inline bool
-checkVL(Slice const& result, std::string expected)
+checkVL(Slice const& result, std::string const& expected)
 {
     Serializer s;
     s.addRaw(result);

src/test/jtx/amount.h

@@ -181,7 +181,7 @@ struct PrettyAsset
 {
 private:
     Asset asset_;
-    std::uint64_t scale_;
+    std::uint32_t scale_;
 
 public:
     template <typename A>

src/test/unit_test/FileDirGuard.h

@@ -29,7 +29,6 @@ OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #include <fstream>
 
 namespace ripple {
-
 namespace detail {
 
 /**