more clippy fixes and annotations

the remaining ones are:
- type complexity
- fns with many arguments
- new() without default()
- false positives for redundant closures (where closure returns a static
  value)
- expected vs actual length check without match/cmp

Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>

pbs-api-types/src/datastore.rs

@@ -1190,7 +1190,7 @@ pub struct TypeCounts {
         },
     },
 )]
-#[derive(Clone, Serialize, Deserialize)]
+#[derive(Clone, Default, Serialize, Deserialize)]
 #[serde(rename_all = "kebab-case")]
 /// Garbage collection status.
 pub struct GarbageCollectionStatus {
@@ -1217,24 +1217,6 @@ pub struct GarbageCollectionStatus {
     pub still_bad: usize,
 }
 
-impl Default for GarbageCollectionStatus {
-    fn default() -> Self {
-        GarbageCollectionStatus {
-            upid: None,
-            index_file_count: 0,
-            index_data_bytes: 0,
-            disk_bytes: 0,
-            disk_chunks: 0,
-            removed_bytes: 0,
-            removed_chunks: 0,
-            pending_bytes: 0,
-            pending_chunks: 0,
-            removed_bad: 0,
-            still_bad: 0,
-        }
-    }
-}
-
 #[api(
     properties: {
         "gc-status": {