Remove OSMLCM_VCA_CACERT

Removes the OSMLCM_VCA_CACERT variable from __lcm__.env in order to fix
the VCA. This works around the parsing of the OSMLCM_VCA_CACERT in
full_install.sh, which currently truncates the cert, causing it to be
invalid.

Change-Id: I8e8c8199bc27ac919e4bf7e6442e6746bb503c8a
Signed-off-by: Adam Israel <adam.israel@canonical.com>