ElasticSearchTTMServer: Rewrite deleteByQuery
This feature is deprecated and will be removed in elastic 2.x
We can workaround with a scroll and deleteIds which provides exactly
the same functionality.
This code adds a direct dependency to the MediaWiki Elastica extension
where MWElasticUtils methods are defined.
NOTE: this code is compatible with elastic 1.7.
Bug: T135213
Depends-On: If540824dad89a5b269166d1d2188f0a518cb5b64
Change-Id: I69bfc0e0d3cc51af3d54476daa4263dcefc87fc6