Fix a bunch of other low-hanging style lints (#36498)

- **Fix a bunch of low hanging style lints like unnecessary-return**
- **Fix single worktree violation**
- **And the rest**

Release Notes:

- N/A

crates/db/src/db.rs

@@ -37,7 +37,7 @@ const FALLBACK_DB_NAME: &str = "FALLBACK_MEMORY_DB";
 const DB_FILE_NAME: &str = "db.sqlite";
 
 pub static ZED_STATELESS: LazyLock<bool> =
-    LazyLock::new(|| env::var("ZED_STATELESS").map_or(false, |v| !v.is_empty()));
+    LazyLock::new(|| env::var("ZED_STATELESS").is_ok_and(|v| !v.is_empty()));
 
 pub static ALL_FILE_DB_FAILED: LazyLock<AtomicBool> = LazyLock::new(|| AtomicBool::new(false));
 

crates/db/src/kvp.rs

@@ -20,7 +20,7 @@ pub trait Dismissable {
         KEY_VALUE_STORE
             .read_kvp(Self::KEY)
             .log_err()
-            .map_or(false, |s| s.is_some())
+            .is_some_and(|s| s.is_some())
     }
 
     fn set_dismissed(is_dismissed: bool, cx: &mut App) {