[BUG] Show index statement failed if user index name has Flint prefix

[dai-chen]

What is the bug?

SHOW FLINT INDEX statement failed if there is user index that happen to have Flint prefix flint_. This issue should apply to all SHOW and DESCRIBE statement because all of them make use of same describeIndex and describeIndexes API in FlintSpark underlying.

How can one reproduce the bug?

1. Create arbitrary skipping index
2. Create a empty OpenSearch index with prefix flint_spark_catalog_
3. Run SHOW FLINT INDEX IN spark_catalog

What is the expected behavior?

Invalid index should be ignored, otherwise one such index will make all show and desc statement unusable.