theme: Remove unused staff parameter for listing themes (#20077)

This PR removes the `staff` parameter for listing themes, as it was not
used.

Release Notes:

- N/A

crates/theme_selector/Cargo.toml

@@ -14,7 +14,6 @@ doctest = false
 
 [dependencies]
 client.workspace = true
-feature_flags.workspace = true
 fs.workspace = true
 fuzzy.workspace = true
 gpui.workspace = true

crates/theme_selector/src/theme_selector.rs

@@ -1,5 +1,4 @@
 use client::telemetry::Telemetry;
-use feature_flags::FeatureFlagAppExt;
 use fs::Fs;
 use fuzzy::{match_strings, StringMatch, StringMatchCandidate};
 use gpui::{
@@ -96,10 +95,9 @@ impl ThemeSelectorDelegate {
     ) -> Self {
         let original_theme = cx.theme().clone();
 
-        let staff_mode = cx.is_staff();
         let registry = <dyn ThemeRegistry>::global(cx);
         let mut themes = registry
-            .list(staff_mode)
+            .list()
             .into_iter()
             .filter(|meta| {
                 if let Some(theme_filter) = themes_filter {