[TEST] Fixed TTL tests for create, index, update
Were failing on faster boxes
Fix visibility in buffered translog
- fix visiblity of last written position in translog
- while there, make sure to properly propagate the exception from sync()
ContextSuggester: Adding couple of tests to catch more bugs

A bunch of minor fixes have been included here, especially due
to wrongly parsed mappings. Also using assertions resulted in an
NPE because they were disabled in the distribution.

Closes #5525