Remove mdadm/ext4 related tasks from Ansible

Description

Closes #45 (closed)

Since every new box is setup using Btrfs, we could remove all the ext4/mdadm related tasks from Ansible to make things a little bit simpler.

Acceptance Criteria

Verify that all obsolete ext4/mdadm related tasks have been removed.

Breakdown

• All the mdadm related tasks seem to be in the roles/install_arch_tasks

• There is a total of 5 tasks

• Each task removal is a separate commit

Type of change

• Maintenance (removal of old redundant/obsolete code)

Possible issues

I am opening this PR as a WIP so that we can act on any potential issues early. Feedback and/or advice is welcome.

How Has This Been Tested?

• ansible-lint has been executed after each change to ensure no lint issues were introduced

Test Configuration:

• OS: Arch Linux
• Toolchain: ansible-lint 4.2.0