MINOR: Fix an off-by-one issue in ValuesTest (#20520)

This test case ensures that the parser can convert ISO8601 correctly.
However, when the local time falls on a different day than the UTC time,
there will be an off-by-one issue.

I changed the test to convert the local time and then compare it with
the expected local time. This should fix the off-by-one issue.

[Reference
link](#18611 (comment))

Reviewers: Andrew Schofield <aschofield@confluent.io>

---------

Signed-off-by: Alex <wenhsuan.alexyu@gmail.com>

Author: WenHsuanYu

connect/api/src/test/java/org/apache/kafka/connect/data/ValuesTest.java

@@ -30,7 +30,6 @@
 import java.nio.charset.StandardCharsets;
 import java.text.SimpleDateFormat;
 import java.time.Instant;
-import java.time.LocalDate;
 import java.time.LocalDateTime;
 import java.time.LocalTime;
 import java.time.ZoneId;
@@ -903,7 +902,7 @@ public void shouldConvertDateValues() {
 
         // ISO8601 strings - accept a string matching pattern "yyyy-MM-dd"
         LocalDateTime localTimeTruncated = localTime.truncatedTo(ChronoUnit.DAYS);
-        java.util.Date d3 = Values.convertToDate(Date.SCHEMA, LocalDate.ofEpochDay(days).format(DateTimeFormatter.ISO_LOCAL_DATE));
+        java.util.Date d3 = Values.convertToDate(Date.SCHEMA, localTime.format(DateTimeFormatter.ISO_LOCAL_DATE));
         LocalDateTime date3 = LocalDateTime.ofInstant(Instant.ofEpochMilli(d3.getTime()), ZoneId.systemDefault());
         assertEquals(localTimeTruncated, date3);