Make LXD installation optional in Charmed Installer

By default lxd cloud is defined, with this change optionally lxd cloud is not
added by passing --small-profile parameter in charmed installer.

Change-Id: I8f3b1816c9f2f43ee6bb84c15b2ce0eda99d691b
Signed-off-by: aticig <gulsum.atici@canonical.com>