refactor: remove dead doWithHeaders/extraHeaders code from CLI API client

internal/cli/api/client.go

@@ -278,16 +278,6 @@ func (client *Client) GetServerInfo() (
 func (client *Client) do(
 	method, path string,
 	body any,
-) ([]byte, error) {
-	return client.doWithHeaders(
-		method, path, body, nil,
-	)
-}
-
-func (client *Client) doWithHeaders(
-	method, path string,
-	body any,
-	extraHeaders map[string]string,
 ) ([]byte, error) {
 	var bodyReader io.Reader
 
@@ -320,10 +310,6 @@ func (client *Client) doWithHeaders(
 		)
 	}
 
-	for key, val := range extraHeaders {
-		request.Header.Set(key, val)
-	}
-
 	resp, err := client.HTTPClient.Do(request)
 	if err != nil {
 		return nil, fmt.Errorf("http: %w", err)