agent: Remove feature flag checks (#30055)

This PR removes all of the feature flag checks related to the Agent.

Tried to do this in the least invasive way possible; we can follow up
with a full removal.

Release Notes:

- N/A

crates/agent/src/message_editor.rs

@@ -17,7 +17,6 @@ use editor::{
     AnchorRangeExt, ContextMenuOptions, ContextMenuPlacement, Editor, EditorElement, EditorEvent,
     EditorMode, EditorStyle, MultiBuffer,
 };
-use feature_flags::{FeatureFlagAppExt, NewBillingFeatureFlag};
 use file_icons::FileIcons;
 use fs::Fs;
 use futures::future::Shared;
@@ -464,10 +463,6 @@ impl MessageEditor {
     }
 
     fn render_max_mode_toggle(&self, cx: &mut Context<Self>) -> Option<AnyElement> {
-        if !cx.has_flag::<NewBillingFeatureFlag>() {
-            return None;
-        }
-
         let thread = self.thread.read(cx);
         let model = thread.configured_model();
         if !model?.model.supports_max_mode() {
@@ -1074,10 +1069,6 @@ impl MessageEditor {
     }
 
     fn render_usage_callout(&self, line_height: Pixels, cx: &mut Context<Self>) -> Option<Div> {
-        if !cx.has_flag::<NewBillingFeatureFlag>() {
-            return None;
-        }
-
         let is_using_zed_provider = self
             .thread
             .read(cx)
@@ -1139,10 +1130,6 @@ impl MessageEditor {
         token_usage_ratio: TokenUsageRatio,
         cx: &mut Context<Self>,
     ) -> Option<Div> {
-        if !cx.has_flag::<NewBillingFeatureFlag>() {
-            return None;
-        }
-
         let title = if token_usage_ratio == TokenUsageRatio::Exceeded {
             "Thread reached the token limit"
         } else {