DRILL-8504: Add Schema Caching to Splunk Plugin #4099

Job	Run time
Run checkstyle and generate protobufs	6m 41s
Run checkstyle and generate protobufs	6m 41s
Main Build (8, default-hadoop)	1h 16m 15s
Main Build (8, default-hadoop)	1h 16m 18s
Main Build (11, default-hadoop)	1h 7m 35s
Main Build (11, default-hadoop)	1h 7m 17s
Main Build (17, default-hadoop)	1h 3m 49s
Main Build (17, default-hadoop)	1h 3m 22s
Main Build (8, hadoop-2)	1h 15m 7s
Main Build (8, hadoop-2)	1h 15m 54s
	9h 38m 59s

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