create lucene index on existing region should not wait for a query to index data

GEODE-3928 is about making sure that after a lucene index is added to an existing region, the data in the region is indexed for queries.

This task is clarifying that we should not wait until a query is executed before indexing the data. The implementation details of GEODE-3928 are vague about whether the indexing will happen immediately or when a query executes.

Acceptance:
After calling create lucene index on an existing region, indexing should begin and stats should reflect that data is added to the index.

Implementation Details:

There may be nothing to do here, depending on how GEODE-3928 is implemented. But if we haven't done anything to eagerly trigger indexing of data, we may need to add a second function to call computeRepository on all members after the index is created on all members.