zed: Remove unnecessary clones (#29513)

`App::http_client` and `Client::http_client` both return an owned `Arc`
which it clones internally. This means we can remove unnecessary clones
when calling these methods.

Release Notes:

- N/A

crates/agent/src/context_picker/completion_provider.rs

@@ -708,7 +708,7 @@ impl CompletionProvider for ContextPickerCompletionProvider {
 
         let thread_store = self.thread_store.clone();
         let editor = self.editor.clone();
-        let http_client = workspace.read(cx).client().http_client().clone();
+        let http_client = workspace.read(cx).client().http_client();
 
         let MentionCompletion { mode, argument, .. } = state;
         let query = argument.unwrap_or_else(|| "".to_string());