Reorder proto validation error message (envoyproxy#38089)

Commit Message: Reorder proto validation error message
Additional Description: As discussed in envoyproxy#38064, the error message is
currently often hard to interpret due to the ordering being "high-level
low-level high-level" rather than the usual high-to-low ordering error
messages have, leading to confusing adjacencies. This is a minimal
reordering that doesn't break tests and makes the error message easier
to read, for example

`Proto constraint validation failed
(HttpProtocolOptionsValidationError.ExplicitHttpConfig: embedded message
failed validation | caused by field: "protocol_config", reason: is
required): explicit_http_config`

becomes

`explicit_http_config: Proto constraint validation failed
(HttpProtocolOptionsValidationError.ExplicitHttpConfig: embedded message
failed validation | caused by field: "protocol_config", reason: is
required)`

Risk Level: Very low it's just an error string.
Testing: Existing tests still pass.
Docs Changes: n/a
Release Notes: n/a
Platform Specific Features: n/a

---------

Signed-off-by: Raven Black <[email protected]>

source/common/protobuf/utility.cc

@@ -209,8 +209,8 @@ void ProtoExceptionUtil::throwMissingFieldException(const std::string& field_nam
 
 void ProtoExceptionUtil::throwProtoValidationException(const std::string& validation_error,
                                                        const Protobuf::Message& message) {
-  std::string error = fmt::format("Proto constraint validation failed ({}): {}", validation_error,
-                                  message.DebugString());
+  std::string error = fmt::format("{}: Proto constraint validation failed ({})",
+                                  message.DebugString(), validation_error);
   throwEnvoyExceptionOrPanic(error);
 }
 
@@ -429,8 +429,8 @@ class PgvCheckVisitor : public ProtobufMessage::ConstProtoVisitor {
     // at which PGV would have stopped because it does not itself check within Any messages.
     if (was_any_or_top_level &&
         !pgv::BaseValidator::AbstractCheckMessage(*reflectable_message, &err)) {
-      std::string error = fmt::format("Proto constraint validation failed ({}): {}", err,
-                                      reflectable_message->DebugString());
+      std::string error = fmt::format("{}: Proto constraint validation failed ({})",
+                                      reflectable_message->DebugString(), err);
       return absl::InvalidArgumentError(error);
     }
     return absl::OkStatus();

test/extensions/string_matcher/lua/lua_test.cc

@@ -91,9 +91,9 @@ TEST(LuaStringMatcher, NoCode) {
 
   LuaStringMatcherFactory factory;
   ::envoy::extensions::string_matcher::lua::v3::Lua empty_config;
-  EXPECT_THROW_WITH_MESSAGE(
+  EXPECT_THROW_WITH_REGEX(
       factory.createStringMatcher(empty_config, context), EnvoyException,
-      "Proto constraint validation failed (LuaValidationError.SourceCode: value is required): ");
+      "Proto constraint validation failed.*LuaValidationError.SourceCode: value is required");
 
   empty_config.mutable_source_code()->set_inline_string("");
   EXPECT_THROW_WITH_MESSAGE(factory.createStringMatcher(empty_config, context), EnvoyException,