Fix robocrys search pagination

[munrojm]

Ensure num_chunks and chunk_size work properly with robocrys search method.

[codecov-commenter]

Codecov Report

Base: 82.04% // Head: 82.04% // No change to project coverage :thumbsup:

Coverage data is based on head (09bf2c0) compared to base (bc5a9fb). Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #712 +/- ## ======================================= Coverage 82.04% 82.04% ======================================= Files 36 36 Lines 1749 1749 ======================================= Hits 1435 1435 Misses 314 314 ``` | [Impacted Files](https://codecov.io/gh/materialsproject/api/pull/712?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=materialsproject) | Coverage Δ | | |---|---|---| | [mp\_api/client/routes/robocrys.py](https://codecov.io/gh/materialsproject/api/pull/712/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=materialsproject#diff-bXBfYXBpL2NsaWVudC9yb3V0ZXMvcm9ib2NyeXMucHk=) | `92.85% <ø> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=materialsproject). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=materialsproject)

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