Release syntax aware heuristic expansion of diagnostic excerpts (#22858)

Implementation PR was #21942

Release Notes:

- Improved diagnostic excerpts by using syntactic info to determine the
context lines to show.

Cargo.lock

@@ -3690,7 +3690,6 @@ dependencies = [
  "ctor",
  "editor",
  "env_logger 0.11.6",
- "feature_flags",
  "gpui",
  "language",
  "log",

crates/diagnostics/Cargo.toml

@@ -18,7 +18,6 @@ collections.workspace = true
 ctor.workspace = true
 editor.workspace = true
 env_logger.workspace = true
-feature_flags.workspace = true
 gpui.workspace = true
 language.workspace = true
 log.workspace = true

crates/diagnostics/src/diagnostics.rs

@@ -14,7 +14,6 @@ use editor::{
     scroll::Autoscroll,
     Editor, EditorEvent, ExcerptId, ExcerptRange, MultiBuffer, ToOffset,
 };
-use feature_flags::FeatureFlagAppExt;
 use gpui::{
     actions, div, svg, AnyElement, AnyView, AppContext, Context, EventEmitter, FocusHandle,
     FocusableView, Global, HighlightStyle, InteractiveElement, IntoElement, Model, ParentElement,
@@ -933,7 +932,6 @@ fn context_range_for_entry(
     snapshot: &BufferSnapshot,
     cx: &AppContext,
 ) -> Range<Point> {
-    if cx.is_staff() {
     if let Some(rows) = heuristic_syntactic_expand(
         entry.range.clone(),
         DIAGNOSTIC_EXPANSION_ROW_LIMIT,
@@ -945,7 +943,6 @@ fn context_range_for_entry(
             end: snapshot.clip_point(Point::new(*rows.end(), u32::MAX), Bias::Left),
         };
     }
-    }
     Range {
         start: Point::new(entry.range.start.row.saturating_sub(context), 0),
         end: snapshot.clip_point(