COMP: Update CTEST_DROP_SITE

Recent cdash changes require that CTEST_DROP_SITE be set to
open.cdash.org path to the CDash installation.

Change-Id: I35260bd3c62e2f26a12d92c396de330dcc631921
Merge topic 'CTEST_DROP_SITE'

148fc130 COMP: Update CTEST_DROP_SITE