refactor: switch wal to sync implementation

[bsbds]

Please briefly answer these questions:

• what problem are you trying to solve? (or if there's no problem, what's the motivation for this change?)

  Switch the curp WAL to synchronous implementation, as the current async version is slow in benchmarks.

• what changes does this pull request make?

• are there any non-obvious implications of these changes? (does it break compatibility with previous versions, etc)

[mergify[bot]]

@bsbds Convert your pr to draft since CI failed

[mergify[bot]]

@bsbds Convert your pr to draft since CI failed

[mergify[bot]]

@bsbds Convert your pr to draft since CI failed

[mergify[bot]]

@bsbds Convert your pr to draft since CI failed

[Phoenix500526]

@Mergifyio rebase

[mergify[bot]]

rebase

✅ Branch has been successfully rebased

[mergify[bot]]

@bsbds Convert your pr to draft since CI failed

[Phoenix500526]

@Mergifyio rebase --autosquash

[mergify[bot]]

rebase --autosquash

✅ Branch has been successfully rebased

[Phoenix500526]

@Mergifyio rebase

[mergify[bot]]

rebase

✅ Branch has been successfully rebased

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 77.67857% with 25 lines in your changes are missing coverage. Please review.

Project coverage is 75.62%. Comparing base (e35b35a) to head (4eed780). Report is 61 commits behind head on master.

Files	Patch %	Lines
crates/curp/src/server/storage/wal/segment.rs	68.25%	7 Missing and 13 partials :warning:
crates/curp/src/server/storage/wal/codec.rs	88.09%	3 Missing and 2 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #705 +/- ## ========================================== + Coverage 75.55% 75.62% +0.06% ========================================== Files 180 187 +7 Lines 26938 27441 +503 Branches 26938 27441 +503 ========================================== + Hits 20353 20752 +399 - Misses 5366 5419 +53 - Partials 1219 1270 +51 ```

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