Revision 1675590

SOLR-7081: TestMiniSolrCloudCluster.testBasics tidies up after itself, adds collection create/delete/create test case.

TestMiniSolrCloudCluster.testBasics now re-creates the server it removed for test purposes,
thus restoring the original NUM_SERVERS count. TestMiniSolrCloudCluster.testBasics now also deletes
the collection it created for test purposes (this revision adds MiniSolrCloudCluster.deleteCollection
and AbstractDistribZkTestBase.waitForCollectionToDisappear methods).

Sometimes TestMiniSolrCloudCluster.testBasics runs its create-collection/search-collection/delete-collection
logic twice, thus creating a create/delete/create-collection test case.