common: increase default zram-fraction to 1.0

The default of 0.5 has proven insufficient on at least 3 boxes so far.

host_vars/debuginfod.archlinux.org/misc

 filesystem: btrfs
 ipv4_address: 168.119.240.111
 ipv6_address: 2a01:4f8:c010:74d4::1
-zram_fraction: 1.0
 wireguard_address: 10.0.0.35
 wireguard_public_key: Wp9ruR2+pCj0TsATuJZiUxk9x6BwcUhXs/yZlmGYjRE=

host_vars/lists.archlinux.org/misc

 filesystem: btrfs
 ipv4_address: 95.217.236.249
-zram_fraction: 1.0
 wireguard_address: 10.0.0.34
 wireguard_public_key: t6Er4qAMe/lWNnAByWdXhbUwXKYfj9CkkJgMp28UQl8=

roles/common/defaults/main.yml

 configure_network: false
 enable_zram_swap: false
+zram_fraction: 1.0

roles/common/templates/zram-generator.conf

 [zram0]
 max-zram-size = none
-{% if zram_fraction is defined %}
 zram-fraction = {{ zram_fraction }}
-{% endif %}