Refactor azure service mesh update function for better readability

Author: deveshdama

src/aks-preview/HISTORY.rst

@@ -12,6 +12,7 @@ To release a new version, please select a new version number (usually plus 1 to
 Pending
 +++++++
 * Deprecate the alias "-r" of parameter --source-resource-id in `az aks trustedaccess rolebinding create`
+* Refactor azure service mesh related code to meet cli style requirements.
 
 1.0.0b4
 +++++++

src/aks-preview/azext_aks_preview/commands.py

@@ -356,7 +356,11 @@ def load_command_table(self, _):
     ) as g:
         g.custom_command("enable", "aks_mesh_enable", supports_no_wait=True)
         g.custom_command(
-            "disable", "aks_mesh_disable", supports_no_wait=True, confirmation=True
+            "disable",
+            "aks_mesh_disable",
+            supports_no_wait=True,
+            confirmation="Existing Azure Service Mesh Profile values will be reset.\n"
+            + "Are you sure you want to perform this operation?"
         )
         g.custom_command(
             "enable-ingress-gateway",

src/aks-preview/azext_aks_preview/custom.py

@@ -2986,7 +2986,7 @@ def _aks_mesh_update(
     )
 
     try:
-        mc = aks_update_decorator.update_mc_profile_default()
+        mc = aks_update_decorator.fetch_mc()
         mc = aks_update_decorator.update_azure_service_mesh_profile(mc)
     except DecoratorEarlyExitException:
         return None