DRILL-4375: Fix the maven release profile
This generated pom file was being discovered and maven was trying to
run the target directory in jdbc-all as a submodule.
This change reverts to the default output location (the module root)
and adds corresponding .gitignore and RAT exclude entries. NOTE:
this is considered bad practice as generated files should appear in
the target directory and be removed upon a maven clean. This default
location is considered to be a known shortcoming of the shade plugin.
Also updated integration test for the jdbc-all jar with small
path change, as changing the location of the dependency-reduced-pom.xml
actually changed the directory the test was being executed from.
Closes #402
