Clear pending staged/unstaged diff hunks hunks when writing to the git index fails (#26173)

Release Notes:

- Git Beta: Fixed a bug where discarding a hunk in the project diff view
performed two concurrent saves of the buffer.
- Git Beta: Fixed an issue where diff hunks appeared in the wrong state
after failing to write to the git index.

crates/project/src/lsp_store.rs

@@ -3184,7 +3184,7 @@ impl LspStore {
                     }
                 }
             }
-            BufferStoreEvent::BufferDropped(_) => {}
+            _ => {}
         }
     }