common: Replace deprecated systemd-swap[1] with zram-generator

zram-generator defaults to 50% of the ram where systemd-swap defaults to
25% of the ram.

[1] https://lists.archlinux.org/pipermail/arch-dev-public/2021-May/030429.html

---

This has already been deployed on dashboards.archlinux.org manually to test the configuration and figure out how to activate it (daemon-reload + restart swap.target).

roles/common/tasks/main.yml

@@ -129,7 +129,7 @@
 - name: install system.conf
   template: src=system.conf.j2 dest=/etc/systemd/system.conf owner=root group=root mode=0644
   notify:
-    - restart swap.target
+    - systemd daemon-reload
 
 - name: install zram-generator
   pacman: name=zram-generator state=present
@@ -138,7 +138,7 @@
 - name: install zram-generator config for zram
   copy: src=zram-generator.conf dest=/etc/systemd/zram-generator.conf owner=root group=root mode=0644
   notify:
-    - systemd daemon-reload
+    - restart swap.target
   when: enable_zram_swap
 
 - name: start systemd-oomd