editoast: refactor infra tests part 7

[hamz2a]

Part of https://github.com/OpenRailAssociation/osrd/issues/6980

It's better to review the PR commit by commit. I created intermediate functions {function}_v2 to facilitate the migration, but I deleted everything at the end.

I also refactored persist_railjson to use DbConnection directly instead of DbConnectionPool. Consequently, I removed the macro persist! that was in there and futures::try_join!, and I added a transaction.

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Codecov Report

Attention: Patch coverage is 82.45614% with 30 lines in your changes missing coverage. Please review.

Project coverage is 28.21%. Comparing base (bea5cee) to head (6b5fd5a). Report is 7 commits behind head on dev.

Files	Patch %	Lines
editoast/src/views/infra/edition.rs	59.37%	13 Missing :warning:
editoast/src/views/infra/mod.rs	66.66%	7 Missing :warning:
editoast/src/views/infra/railjson.rs	54.54%	5 Missing :warning:
editoast/src/views/infra/routes.rs	57.14%	3 Missing :warning:
editoast/src/views/infra/auto_fixes/mod.rs	77.77%	2 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #7932 +/- ## ============================================ - Coverage 28.25% 28.21% -0.05% Complexity 2075 2075 ============================================ Files 1276 1276 Lines 156193 156314 +121 Branches 3084 3084 ============================================ - Hits 44136 44102 -34 - Misses 110216 110371 +155 Partials 1841 1841 ``` | [Flag](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7932/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [core](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7932/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `75.03% <ø> (ø)` | | | [editoast](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7932/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `70.79% <82.45%> (-0.23%)` | :arrow_down: | | [front](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7932/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `9.91% <ø> (-0.01%)` | :arrow_down: | | [gateway](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7932/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `2.34% <ø> (ø)` | | | [railjson_generator](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7932/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `87.49% <ø> (ø)` | | | [tests](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7932/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `72.93% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#carryforward-flags-in-the-pull-request-comment) to find out more.

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[hamz2a]

I'm curious about why we do need a lot of #[serial_test::serial] in commit 3040c34.

I added #[serial_test::serial] because I was getting deadlock errors.

[woshilapin]

I'm curious about why we do need a lot of #[serial_test::serial] in commit 3040c34.

I added #[serial_test::serial] because I was getting deadlock errors.

We dug a little bit to try to understand. It's a deadlock detected by the Postgresql instance itself. It might be due to concurrence on the generated id for infras since we do create very long transactions when working with infras in tests.

We did not find an obvious solution to work around the problem. Let's keep it like this.