dashboard: run node_export as privileged container

dashboard: run node_export as privileged container

Typical error:

```
type=AVC msg=audit(1575367499.582:3210): avc:  denied  { search } for  pid=26680 comm="node_exporter" name="1" dev="proc" ino=11528 scontext=system_u:system_r:container_t:s0:c100,c1014 tcontext=system_u:system_r:init_t:s0 tclass=dir permissive=0
```

node_exporter needs to be run as privileged to avoid avc denied error
since it gathers lot of information on the host.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1762168
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
(cherry picked from commit d245eb7e7d9453af04e141ed0abd3fbdef1e563c)