Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1322

I am not using this bridge and haven't tested this but multiple people have said 1.5.0 isn't working and 1.8.0 works for them so it seems to make sense to update.

https://github.com/matrix-org/matrix-appservice-slack/issues/618#issuecomment-929849093

Minor fixes to the still broken Corporal section

Add new Discord AppService Bridge to matrix-awx role.

for matrix_nginx_proxy_proxy_synapse_metrics_basic_auth_key
resolves #1308

Seems like Ubuntu 18.04 does not have a dedicated `systemd-timesyncd` package, nor
does it include the `systemd-timesyncd` binary in the main `systemd` package.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/1302

Regression since https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/1192

#1192 lead to the following error for me on Archlinux:
`TASK [matrix-base : Install host dependencies] *******************************************************************************************************************************
fatal: [matrix.***.de]: FAILED! => changed=false 
  msg: |-
    failed to install systemd-timesyncd: error: target not found: systemd-timesyncd`

There is no package called `systemd-timesyncd` on Archlinux. The service is installed with the [`systemd`](https://archlinux.org/packages/core/x86_64/systemd/) package itself.

I suggest removing the `systemd-timesyncd` from 2453876eb9/roles/matrix-base/tasks/server_base/setup_archlinux.yml (L7)

From 6f80292745