agent: Don't render trial upsell when not using the Zed provider (#30029)

This PR makes it so we don't render the trial upsell when not using the
Zed provider.

Release Notes:

- Agent Beta: Changed Zed Pro trial upsell to only be displayed when
using a model through the Zed provider.

crates/agent/src/assistant_panel.rs

@@ -27,7 +27,9 @@ use gpui::{
     linear_gradient, prelude::*, pulsating_between,
 };
 use language::LanguageRegistry;
-use language_model::{LanguageModelProviderTosView, LanguageModelRegistry, RequestUsage};
+use language_model::{
+    LanguageModelProviderTosView, LanguageModelRegistry, RequestUsage, ZED_CLOUD_PROVIDER_ID,
+};
 use language_model_selector::ToggleModelSelector;
 use project::{Project, ProjectPath, Worktree};
 use prompt_store::{PromptBuilder, PromptStore, UserPromptId};
@@ -1806,6 +1808,19 @@ impl AssistantPanel {
             return false;
         }
 
+        let is_using_zed_provider = self
+            .thread
+            .read(cx)
+            .thread()
+            .read(cx)
+            .configured_model()
+            .map_or(false, |model| {
+                model.provider.id().0 == ZED_CLOUD_PROVIDER_ID
+            });
+        if !is_using_zed_provider {
+            return false;
+        }
+
         let plan = self.user_store.read(cx).current_plan();
         if matches!(plan, Some(Plan::ZedPro | Plan::ZedProTrial)) {
             return false;