## What changes were proposed in this pull request?
I've found some minor issues in "show tables" command:
1. In the `SessionCatalog.scala`, `listTables(db: String)` method will call `listTables(formatDatabaseName(db), "*")` to list all the tables for certain db, but in the method `listTables(db: String, pattern: String)`, this db name is formatted once more. So I think we should remove
`formatDatabaseName()` in the caller.
2. I suggest to add sort to listTables(db: String) in InMemoryCatalog.scala, just like listDatabases().
## How was this patch tested?
The existing test cases should cover it.
Author: bomeng <bmeng@us.ibm.com>
Closes#13695 from bomeng/SPARK-15978.
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