### What changes were proposed in this pull request?
Now that we merged the Koalas main code into the PySpark code base (#32036), we should port the Koalas Index unit tests to PySpark.
### Why are the changes needed?
Currently, the pandas-on-Spark modules are not tested fully. We should enable the Index unit tests.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Enable Index unit tests.
Closes#32139 from xinrong-databricks/port.indexes_tests.
Authored-by: Xinrong Meng <xinrong.meng@databricks.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>