install_arch: Use compress-force=zstd instead of compress=zstd

Btrfs by default has a pretty stupid algorithm that checks for whether a file is
compressable or not. In practice this algorithm is pretty slow in my tests and
just directly passing the file to zstd is faster. I'm running compress-force=zstd
on all my machines now and it seems safe. Let's roll with this.

roles/install_arch/tasks/main.yml

@@ -210,7 +210,7 @@
   lineinfile:
     path: /mnt/etc/default/grub
     regexp: "^GRUB_CMDLINE_LINUX_DEFAULT="
-    line: "GRUB_CMDLINE_LINUX_DEFAULT=\"rootflags=compress=zstd\""
+    line: "GRUB_CMDLINE_LINUX_DEFAULT=\"rootflags=compress-force=zstd\""
   when: filesystem == "btrfs"
 
 - name: install grub