base: Rename the ospack file to a neutral "rootfs"

Downstreams need to figure out what is specific to Apertis and needs to
be customized, so let's not mislead them and drop "apertis" from the
rootfs intermediate artifact as it does not need any customization since
it's purely internal to the pipeline.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

base/Dockerfile

@@ -25,7 +25,7 @@ ENV LC_ALL=C.UTF-8
 
 ARG DEBIAN_FRONTEND=noninteractive
 
-ARG OSPACK=apertis.tar.gz
+ARG OSPACK=rootfs.tar.gz
 ADD ${OSPACK} /
 
 # Always install procps in case the docker file gets used in jenkins

base/rootfs.yaml

 {{- $architecture := or .architecture "amd64" }}
 {{- $mirror := or .mirror "https://repositories.apertis.org/apertis/" -}}
 {{- $suite := or .suite "v2020dev0" -}}
-{{- $ospack := or .ospack "apertis.tar.gz" -}}
+{{- $ospack := or .ospack "rootfs.tar.gz" -}}
 {{- $timestamp := or .timestamp "00000000.0" -}}
 {{- $stable := or .stable "" -}}