This PR addresses to fix (#31308) a race condition where auto-indent (in
buffer.cs) and on-type-formatting (in lsp_store.rs) concurrently
calculate indentation using the same buffer snapshot.

Previous Solution (Abandoned): 
https://github.com/zed-industries/zed/pull/31340

Final Solution:
Delay applying on-type-formatting until auto-indent is complete.

Issue:

If AutoindentMode finishes first, formatting works correctly. If
"Formatting on typing" starts before AutoindentMode completes, it
results in double indentation.

Closes #31308

Release Notes:

- Fixed a race condition resulting in incorrect buffer contents when combining auto-indent and on-type-formatting