chore(agent): Replace operator_libs_linux with charmlibs (#899)

* chore(agent): add charmlibs to requirements.txt

* chore(agent): add charmlibs to charm dependency group

* chore(agent): use charmlibs instead of operator_libs_linux

* chore(agent): remove operator_libs_linux

Author: pedro-avalos

agent/charms/testflinger-agent-host-charm/charmcraft.yaml

@@ -33,12 +33,6 @@ platforms:
   amd64:
 
 charm-libs:
-  - lib: operator_libs_linux.apt
-    version: "0"
-  - lib: operator_libs_linux.passwd
-    version: "0"
-  - lib: operator_libs_linux.systemd
-    version: "1"
   - lib: grafana_agent.cos_agent
     version: "0"
 
@@ -99,5 +93,5 @@ parts:
       craftctl default
 
 provides:
-    cos-agent:
-        interface: cos_agent
+  cos-agent:
+    interface: cos_agent