Cannot take snapshots on Windows due to map_size and page_size values

Describe the bug Index scheduler fails to initialize during snapshot creation on Windows, leading to an internal error and the inability to create snapshots.

To Reproduce Steps to reproduce the behavior:

1. Run Meilisearch on Windows (x86) with default options
2. Attempt to create snapshot
3. Snapshot fails with the following error:

Batch failed while doing: {"steps":[{"currentStep":"processing tasks","finished":0,"total":2},{"currentStep":"snapshot the index scheduler","finished":1,"total":6}],"percentage":8.333334}

Batch failed map size (1310824018739) must be a multiple of the system page size (4096)

Expected behavior The snapshot succeeds

Screenshots If applicable, add screenshots to help explain your problem.

Meilisearch version: Reproduced on v1.27.0 and v1.29.0

Additional context We have done analysis of the code where the error originates (found via trace logging) and we believe there is a missing call to clamp_to_page_size here

We see that the DEFAULT_BUDGET on Windows is 6TiB:

const DEFAULT_BUDGET: usize = 6 * 1024 * 1024 * 1024 * 1024; // 6 TiB, 1 index

Naturally, this properly fits into the default page size of 4KiB (4096) for x86-64 machines:

6597069766656÷4096 = 1610612736

Given the following trace logs, we can further deduce what happens in the function to make things go awry:

memmap budget: 6597069766656B
index budget: 3277060046848B
1 index of 1310824018739B can be opened simultaneously.

With the default task_db_size of 20GiB here and a default base_map_size set to the max index size (2TiB) here we can trace the calculations:

let mut budget = budget / 2;  # 3298534883328
...

budget -= task_db_size;  # 3277060046848 (value from trace log)
...
let mut index_count = budget / base_map_size;   # 1.490234375 < 2 -> enter the conditional
...
let map_size = (budget * 2) / 5;  # 1310824018739.2 floored to the value from the trace

This gets returned as the map_size and instantly fails when passed off to heed: 1310824018739 mod 4096 = 819

If we clamped the map_size to the page size before returning, we believe the issue would be fixed.