Remove checkindex -exorcise [LUCENE-6344]

There is just no excuse to have such a horrible option here. If someone wants to delete their data, they can do it themselves. This is such a trap.

---
Migrated from [LUCENE-6344](https://issues.apache.org/jira/browse/LUCENE-6344) by Robert Muir (@rmuir)

Start with the CheckIndex entry point named in the issue and determine where the -exorcise option is defined and covered by tests. Confirm the option's current behavior before removing it, then run the relevant CheckIndex tests; done means the option is no longer available and those tests pass.

Written by the indexing model from the issue text.