Remove start clause from a significant portion of the cypher documentation.

o Approx 120 docs tests no longer have a START clause.
o Some tests with START clauses have optional part of MATCH clauses, and so are left untouched.

Notes:
o Deleting nodes using the START-free syntax still breaks, this remains to do
Imports
Fixes an issue with closing index readers for transaction-less read-only
statement contexts. There was an old IndexReaderFactory implementation
used that assumed a global single instance read-only statement context
still left.