unconditionally include linux install tasks

These are also responsible for setting up the installer, and doing some
bookkeeping around our GPG keys.
The installation of the agent package itself is already gated behind
agent_datadog_skip_install, so we won't attemp to reinstall the agent if
it's already installed to the latest version.
However we will now correctly probe for the installer ownership.
This should fix #603

tasks/main.yml

@@ -35,7 +35,7 @@
 
 - name: Debian Install Tasks
   include_tasks: pkg-debian.yml
-  when: ansible_facts.os_family == "Debian" and not agent_datadog_skip_install
+  when: ansible_facts.os_family == "Debian"
 
 - name: Include tasks to remove old GPG keys
   include_tasks: _remove_rpm_keys.yml
@@ -50,11 +50,11 @@
 # For Rocky it is some 4.X and >= 5.0
 - name: RedHat Install Tasks
   include_tasks: pkg-redhat.yml
-  when: ansible_facts.os_family in ["RedHat", "Rocky", "AlmaLinux"] and not agent_datadog_skip_install
+  when: ansible_facts.os_family in ["RedHat", "Rocky", "AlmaLinux"]
 
 - name: Suse Install Tasks
   include_tasks: pkg-suse.yml
-  when: ansible_facts.os_family == "Suse" and not agent_datadog_skip_install
+  when: ansible_facts.os_family == "Suse"
 
 # Note we don't check agent_datadog_skip_install variable value for windows here,
 # because some tasks in pkg-windows.yml are carried out regardless of its value.