kubectl: avoid conflict with existing f aliases in kca alias (#8625)

plugins/kubectl/kubectl.plugin.zsh

@@ -14,7 +14,7 @@ fi
 alias k=kubectl
 
 # Execute a kubectl command against all namespaces
-alias kca='f(){ kubectl "$@" --all-namespaces;  unset -f f; }; f'
+alias kca='_kca(){ kubectl "$@" --all-namespaces;  unset -f _kca; }; _kca'
 
 # Apply a YML file
 alias kaf='kubectl apply -f'