Drop states using 'onlyif' condition

This is broken in salt 3000 (saltstack/salt#56131) currently shipped in
Fedora 30. Since those states apply changes already incorporated in all
released templates (and latest stable installation image), simply drop
them to unbreak updates.

Fixes QubesOS/qubes-issues#5705

update/qubes-vm.sls

@@ -7,32 +7,6 @@ dsa-4371-update:
     - stateful: True
 {% endif %}
 
-{% if grains['oscodename'] == 'stretch' %}
-# remove jessie-backports erroneously added to stretch template
-/etc/apt/sources.list:
-  file.line:
-    - mode: delete
-    - content: "https://deb.debian.org/debian jessie-backports main"
-    - onlyif:
-      - test -f /etc/apt/sources.list
-{% endif %}
-
-# Migrate to new onion repositories automatically, even if the user modified
-# the repository file (in which case rpm do not automatically replace it)
-/etc/yum.repos.d/qubes-r4.repo:
-  file.replace:
-    - pattern: sik5nlgfc5qylnnsr57qrbm64zbdx6t4lreyhpon3ychmxmiem7tioad
-    - repl: qubesosfasa4zl44o4tws22di6kepyzfeqv3tg4e3ztknltfxqrymdad
-    - onlyif:
-      - test -f /etc/yum.repos.d/qubes-r4.repo
-
-/etc/apt/sources.list.d/qubes-r4.list:
-  file.replace:
-    - pattern: sik5nlgfc5qylnnsr57qrbm64zbdx6t4lreyhpon3ychmxmiem7tioad
-    - repl: qubesosfasa4zl44o4tws22di6kepyzfeqv3tg4e3ztknltfxqrymdad
-    - onlyif:
-      - test -f /etc/apt/sources.list.d/qubes-r4.list
-
 {% if grains['os'] == 'Fedora' %}
 # workaround for https://bugzilla.redhat.com/1669247
 dnf list updates --refresh >/dev/null: