internal/conformance: update failing tests list, add comments

Change-Id: Iafac20dc4e29e635e05cfcab11c7a06178b99174
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/600395
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Christian Höppner <hoeppi@google.com>

internal/conformance/failing_tests_text_format.txt

@@ -1,10 +1,10 @@
-Recommended.Editions_Proto3.ProtobufInput.MessageUnknownFields_Print.TextFormatOutput
-Recommended.Editions_Proto3.TextFormatInput.StringLiteralShortUnicodeEscapeSurrogatePairBytes
-Recommended.Editions_Proto3.TextFormatInput.StringLiteralShortUnicodeEscapeSurrogatePairString
-Recommended.Editions_Proto3.TextFormatInput.StringLiteralUnicodeEscapeSurrogatePairLongShortBytes
-Recommended.Editions_Proto3.TextFormatInput.StringLiteralUnicodeEscapeSurrogatePairLongShortString
-Recommended.Proto3.ProtobufInput.MessageUnknownFields_Print.TextFormatOutput
-Recommended.Proto3.TextFormatInput.StringLiteralShortUnicodeEscapeSurrogatePairBytes
-Recommended.Proto3.TextFormatInput.StringLiteralShortUnicodeEscapeSurrogatePairString
-Recommended.Proto3.TextFormatInput.StringLiteralUnicodeEscapeSurrogatePairLongShortBytes
-Recommended.Proto3.TextFormatInput.StringLiteralUnicodeEscapeSurrogatePairLongShortString
+Recommended.Editions_Proto3.ProtobufInput.MessageUnknownFields_Print.TextFormatOutput                              # TEXT_FORMAT output we received from test was unparseable.
+Recommended.Editions_Proto3.TextFormatInput.StringLiteralShortUnicodeEscapeSurrogatePairBytes                      # Should have failed to parse, but didn't.
+Recommended.Editions_Proto3.TextFormatInput.StringLiteralShortUnicodeEscapeSurrogatePairString                     # Should have failed to parse, but didn't.
+Recommended.Editions_Proto3.TextFormatInput.StringLiteralUnicodeEscapeSurrogatePairLongShortBytes                  # Should have failed to parse, but didn't.
+Recommended.Editions_Proto3.TextFormatInput.StringLiteralUnicodeEscapeSurrogatePairLongShortString                 # Should have failed to parse, but didn't.
+Recommended.Proto3.ProtobufInput.MessageUnknownFields_Print.TextFormatOutput                                       # TEXT_FORMAT output we received from test was unparseable.
+Recommended.Proto3.TextFormatInput.StringLiteralShortUnicodeEscapeSurrogatePairBytes                               # Should have failed to parse, but didn't.
+Recommended.Proto3.TextFormatInput.StringLiteralShortUnicodeEscapeSurrogatePairString                              # Should have failed to parse, but didn't.
+Recommended.Proto3.TextFormatInput.StringLiteralUnicodeEscapeSurrogatePairLongShortBytes                           # Should have failed to parse, but didn't.
+Recommended.Proto3.TextFormatInput.StringLiteralUnicodeEscapeSurrogatePairLongShortString                          # Should have failed to parse, but didn't.