scripts/build_utils: populate DEB_BUILD_PROFILES using dist/other_envvars

scripts/build_utils: populate DEB_BUILD_PROFILES using dist/other_envvars

* rename PROFILES to DEB_BUILD_PROFILES so it's more explicit that
  DEB_BUILD_PROFILES is for debian package build
* populate DEB_BUILD_PROFILES using dist/other_envvars, so that
  this environment variable can be populate to the next jenkins job.
  as dist/other_envvars is specified as one of the "properties-file"s
  in ceph-*build/config/definitions/ceph-build.yml and
* pass DEB_BUILD_PROFILES to pbuilder via an environment
  variable with the same name. more consistent this way, as
  DEB_BUILD_OPTIONS is also passed this way.

Signed-off-by: Kefu Chai <kchai@redhat.com>