Pool search at depth one but SearchQuery defaults to depth zero

[pallix]

I think it's super confusing that pool search at depth 1 by default:

https://github.com/liqd/adhocracy3.mercator/blob/406345f084c7fd05d7c82f6479deb8c9123c2542/src/adhocracy_core/adhocracy_core/sheets/pool.py#L45

but the search_query has an infinite depth (depth is zero).

[pallix]

This caused the #1140 bug when refactoring a migration script and omitting the depth.

[joka]

I propose to set the default to inifite in both cases, we should ask the fronten team if this makes any trouble.

[xi]

I don't expect issues. @nidico what about you?

[nidico]

I'm fine with infinite depth by default if this makes no difference performance-wise in the backend.

[joka]

I'm fine with infinite depth by default if this makes no difference performance-wise in the back

we need to test this

[xi]

I would also be fine with a depth of 1 everywhere.