[HUDI-1870] Add more Spark CI build tasks (#4022)

* [HUDI-1870] Add more Spark CI build tasks

- build for spark3.0.x
- build for spark-shade-unbundle-avro
- fix build failures
  - delete unnecessary assertion for spark 3.0.x
  - use AvroConversionUtils#convertAvroSchemaToStructType instead of calling SchemaConverters#toSqlType directly to solve the compilation failures with spark-shade-unbundle-avro (#5)

Co-authored-by: Yann <biyan900116@gmail.com>

hudi-spark-datasource/hudi-spark3/src/test/java/org/apache/hudi/spark3/internal/TestReflectUtil.java

@@ -50,9 +50,5 @@ public class TestReflectUtil extends HoodieClientTestBase {
 
     Assertions.assertTrue(
         ((UnresolvedRelation)newStatment.table()).multipartIdentifier().contains("test_reflect_util"));
-
-    if (!spark.version().startsWith("3.0")) {
-      Assertions.assertTrue(newStatment.userSpecifiedCols().isEmpty());
-    }
   }
 }