HPCC-10595 Don't display ecl-packagemap-validate success on warnings

Other warnings prevent the output of "validation successful" but warnings
about files that are unmapped or not in dfs currently don't prevent that
message.  Make all warnings behave consistently in this regard.

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Merge pull request #5354 from afishbeck/ecl-packagemap-validate-strict

HPCC-10595 Don't display ecl-packagemap-validate success on warnings

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>