[SPARK-26499][SQL][FOLLOW-UP] Replace update with setByte for ByteType in JdbcUtils.makeGetter

### What changes were proposed in this pull request?

This is a follow-up pr to fix the code coming from apache#23400; it replaces `update` with `setByte` for ByteType in `JdbcUtils.makeGetter`.

### Why are the changes needed?

For better code.

### Does this PR introduce any user-facing change?

No.

### How was this patch tested?

Existing tests.

Closes apache#26532 from maropu/SPARK-26499-FOLLOWUP.

Authored-by: Takeshi Yamamuro <[email protected]>
Signed-off-by: Sean Owen <[email protected]>

Author: maropu

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JdbcUtils.scala

@@ -445,7 +445,7 @@ object JdbcUtils extends Logging {
 
     case ByteType =>
       (rs: ResultSet, row: InternalRow, pos: Int) =>
-        row.update(pos, rs.getByte(pos + 1))
+        row.setByte(pos, rs.getByte(pos + 1))
 
     case StringType =>
       (rs: ResultSet, row: InternalRow, pos: Int) =>