[BugFix] fix character set issues of string literal in jdbc (#51177)

Signed-off-by: ShaoxunLi <[email protected]>

fe/fe-core/src/main/java/com/starrocks/analysis/StringLiteral.java

@@ -283,7 +283,7 @@ public void parseMysqlParam(ByteBuffer data) {
         }
         byte[] bytes = new byte[strLen];
         data.get(bytes);
-        value = new String(bytes);
+        value = new String(bytes, StandardCharsets.UTF_8);
     }
 
     public static StringLiteral create(String value) {