Revert "Temporary fix of failing aria2 on centos"

The fix is no longer needed since a fixed aria2 package has been promoted in epel.

See https://bugzilla.redhat.com/show_bug.cgi?id=1704413

This is a revert of the following changes:
I7770c5417feacfc43a3ad8801125603a55ba9ea8
I26d3c9338247ffc789bf4a5291e65e954151cc51
I4ec91f541e6d2d4cca4d899f4c7d519b169e2f50

Change-Id: Ia181556e77dcc85bea726e47fc8ca1f097cc3bbb

tasks/lxc_cache_preparation_systemd_new.yml

@@ -23,25 +23,12 @@
   when:
     - lxc_image_cache_refresh | bool
 
-- block:
-    - name: Ensure image has been pre-staged
-      async_status:
-        jid: "{{ prestage_image.ansible_job_id }}"
-      register: job_result
-      until: job_result.finished
-      retries: 60
-  rescue:
-    - name: Trying to download image with alternate method
-      get_url:
-        url: "{{ lxc_hosts_container_image_url }}"
-        dest: "/tmp/{{ cache_basename }}"
-        validate_certs: "{{ (lxc_hosts_validate_certs | bool) | lower }}"
-        force: true
-        timeout: 15
-      register: image_download
-      until: image_download is success
-      retries: 3
-      delay: 2
+- name: Ensure image has been pre-staged
+  async_status:
+    jid: "{{ prestage_image.ansible_job_id }}"
+  register: job_result
+  until: job_result.finished
+  retries: 60
 
 - name: Ensure systemd-importd is enabled
   systemd:

tasks/lxc_cache_preparation_systemd_old.yml

@@ -32,25 +32,12 @@
   when:
     - lxc_image_cache_refresh | bool
 
-- block:
-    - name: Ensure image has been pre-staged
-      async_status:
-        jid: "{{ prestage_image.ansible_job_id }}"
-      register: job_result
-      until: job_result.finished
-      retries: 60
-  rescue:
-    - name: Trying to download image with alternate method
-      get_url:
-        url: "{{ lxc_hosts_container_image_url }}"
-        dest: "/tmp/{{ cache_basename }}"
-        validate_certs: "{{ (lxc_hosts_validate_certs | bool) | lower }}"
-        force: true
-        timeout: 15
-      register: image_download
-      until: image_download is success
-      retries: 3
-      delay: 2
+- name: Ensure image has been pre-staged
+  async_status:
+    jid: "{{ prestage_image.ansible_job_id }}"
+  register: job_result
+  until: job_result.finished
+  retries: 60
 
 - name: Place container rootfs
   unarchive: