obs/slapos: fix use shorter name

fixup for 203927d9

The old tarball was not removed correctly

obs/slapos/prepare_obs_upload.sh

@@ -10,7 +10,7 @@ cd $OBS_DIRECTORY
 osc up
 
 # Remove former configuration
-osc rm -f $SLAPOS_ORGINAL_DIRECTORY*.tar.gz
+osc rm -f $SLAPOS_DIRECTORY_PREFIX*.tar.gz
 osc rm -f slapos.spec
 
 # Prepare new tarball

obs/slapos/release_configuration.sh

@@ -15,7 +15,8 @@ OBS_DIRECTORY=$CURRENT_DIRECTORY/home:VIFIBnexedi:branches:home:VIFIBnexedi/Slap
 
 TEMPLATES_DIRECTORY=$CURRENT_DIRECTORY/templates
 SLAPOS_ORGINAL_DIRECTORY=slapos-node
-SLAPOS_DIRECTORY=sn_$VERSION+$RECIPE_VERSION+$RELEASE
+SLAPOS_DIRECTORY_PREFIX=sn
+SLAPOS_DIRECTORY=${SLAPOS_DIRECTORY_PREFIX}_$VERSION+$RECIPE_VERSION+$RELEASE
 
 VERSION_REGEX="s/\%RECIPE_VERSION\%/$RECIPE_VERSION/g;s/\%VERSION\%/$VERSION/g;s/\%RELEASE\%/$RELEASE/g;s/\%SLAPOS_DIRECTORY\%/$SLAPOS_DIRECTORY/g"
 export SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt