refactor: clean up uses of std::source_location (#6272)

Since the minimum Clang version we support is 16, the checks for version < 15 are no longer necessary. This change therefore removes the macros checking if the clang version is < 15 and simplifies uses of `std::source_location`.

src/test/jtx/TestHelpers.h

@@ -15,15 +15,8 @@
 #include <xrpl/protocol/Units.h>
 #include <xrpl/protocol/jss.h>
 
-#include <vector>
-
-#if (defined(__clang_major__) && __clang_major__ < 15)
-#include <experimental/source_location>
-using source_location = std::experimental::source_location;
-#else
 #include <source_location>
-using std::source_location;
-#endif
+#include <vector>
 
 namespace xrpl {
 namespace test {
@@ -640,7 +633,7 @@ checkMetrics(
     std::size_t expectedPerLedger,
     std::uint64_t expectedMinFeeLevel = baseFeeLevel.fee(),
     std::uint64_t expectedMedFeeLevel = minEscalationFeeLevel.fee(),
-    source_location const location = source_location::current())
+    std::source_location const location = std::source_location::current())
 {
     int line = location.line();
     char const* file = location.file_name();

src/test/rpc/LedgerEntry_test.cpp

@@ -14,13 +14,7 @@
 #include <xrpl/protocol/STXChainBridge.h>
 #include <xrpl/protocol/jss.h>
 
-#if (defined(__clang_major__) && __clang_major__ < 15)
-#include <experimental/source_location>
-using source_location = std::experimental::source_location;
-#else
 #include <source_location>
-using std::source_location;
-#endif
 namespace xrpl {
 
 namespace test {
@@ -114,7 +108,7 @@ class LedgerEntry_test : public beast::unit_test::suite
         Json::Value const& jv,
         std::string const& err,
         std::string const& msg,
-        source_location const location = source_location::current())
+        std::source_location const location = std::source_location::current())
     {
         if (BEAST_EXPECT(jv.isMember(jss::status)))
             BEAST_EXPECTS(
@@ -297,7 +291,7 @@ class LedgerEntry_test : public beast::unit_test::suite
         FieldType const typeID,
         std::string const& expectedError,
         bool required = true,
-        source_location const location = source_location::current())
+        std::source_location const location = std::source_location::current())
     {
         forAllApiVersions([&, this](unsigned apiVersion) {
             if (required)
@@ -350,7 +344,7 @@ class LedgerEntry_test : public beast::unit_test::suite
         FieldType typeID,
         std::string const& expectedError,
         bool required = true,
-        source_location const location = source_location::current())
+        std::source_location const location = std::source_location::current())
     {
         forAllApiVersions([&, this](unsigned apiVersion) {
             if (required)
@@ -407,7 +401,7 @@ class LedgerEntry_test : public beast::unit_test::suite
     runLedgerEntryTest(
         test::jtx::Env& env,
         Json::StaticString const& parentField,
-        source_location const location = source_location::current())
+        std::source_location const location = std::source_location::current())
     {
         testMalformedField(
             env,
@@ -431,7 +425,7 @@ class LedgerEntry_test : public beast::unit_test::suite
         test::jtx::Env& env,
         Json::StaticString const& parentField,
         std::vector<Subfield> const& subfields,
-        source_location const location = source_location::current())
+        std::source_location const location = std::source_location::current())
     {
         testMalformedField(
             env,