Fix quotation of nerdctl_extra_flags (#8668)

Due to missing quotation of nerdctl_extra_flags, ansible-playbook was failed:

  Using module file /usr/local/lib/python3.6/dist-packages/ansible/modules/command.py
  Pipelining is enabled.
    [..]
    File "/usr/lib/python3.8/shlex.py", line 191, in read_token
      raise ValueError("No closing quotation")

This fixes the issue.

T-Eberle investigated the issue and found the solution.
Thank you T-Eberle!

roles/download/defaults/main.yml

@@ -65,7 +65,7 @@ image_info_command_on_localhost: "{{ lookup('vars', image_command_tool_on_localh
 image_arch: "{{host_architecture | default('amd64')}}"
 
 # Nerdctl insecure flag set
-nerdctl_extra_flags: '{%- if containerd_insecure_registries is defined and containerd_insecure_registries|length>0 -%}\" --insecure-registry"{%- else -%}{%- endif -%}'
+nerdctl_extra_flags: '{%- if containerd_insecure_registries is defined and containerd_insecure_registries|length>0 -%}\" --insecure-registry\"{%- else -%}{%- endif -%}'
 
 # Versions
 kubeadm_version: "{{ kube_version }}"