refactor: drop ineffective remote_src from copy tasks

All tasks writing the concatenated chain, fullchain and all files pass the file
body via `content`. The `remote_src` option only governs how `src` is resolved
and is ignored in that case, so it merely suggested a behaviour the tasks never
had.

Co-authored-by: Copilot <copilot@github.com>

tasks/client_certificate.yaml

@@ -68,7 +68,6 @@
       owner: "root"
       group: "root"
       mode: "0644"
-      remote_src: true
     when: _stat_result.stat.exists is defined and
           _stat_result.stat.exists
 
@@ -96,7 +95,6 @@
       owner: "root"
       group: "root"
       mode: "0644"
-      remote_src: true
     when: _stat_result.stat.exists is defined and
           _stat_result.stat.exists
 
@@ -124,6 +122,5 @@
       owner: "root"
       group: "root"
       mode: "0600"
-      remote_src: true
     when: _stat_result.stat.exists is defined and
           _stat_result.stat.exists