Revert "Feature 8839: Modified Installation script to install OSM with NGUI. Default installation is with light-ui. -n ngui will install OSM with NGUI. Resolved merge conflict. Added NG-UI to ci_stage_3."

This reverts commit 98a5b631.

Change-Id: Iccc5fcf6605015c36792d2f94d0afe7c4d1c1edf
Signed-off-by: beierlm <mark.beierl@canonical.com>