CDH-22845: Reduce Expr.EXPR_DEPTH_LIMIT to work with Java 8.

Java 8 seems to have larger stack frames, which broke unittest
AnalyzeExprsTest.TestExprDepthLimit.  It starts to break with a depth limit
of 1181.  Choosing 1000 down from 1500 conservatively.

Change-Id: I4e04bb55590a0af907f661e18dbfb2d11407e8ac
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/5232
Reviewed-by: Ishaan Joshi <ishaan@cloudera.com>
Tested-by: jenkins