Compare tidwall/btree vs google/btree

## Task
the [benchmark ](https://github.com/tidwall/btree-benchmark/tree/generics#btree-benchmark) shows tidwall/btree has a better performance. We can consider use `tidwall/btree` If **generic** is stable. We can benchmark performance to see if it can improve our current meta-information maintenance performance in PD.

- [tidwall/btree](https://github.com/tidwall/btree)
- [google/btree](https://github.com/google/btree)

## Related issue
- https://github.com/tikv/pd/pull/1184
- https://github.com/tikv/pd/issues/3635