FE Cleanup: Use analyzeNoThrow() and investigate Expr.substitute() TODO.

I looked at those places that call Expr.substitute/List() and I think
that for all of them we do not want preserveRootType, so I simply
removed the TODO.

Change-Id: I7c98e2aee8f11b14781ec49840e82e69adc6b751
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4841
Tested-by: jenkins
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: Alex Behm <alex.behm@cloudera.com>