sage_setup: Separate installing and cleaning

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This is preparation for #28925.


Depends on #30779

CC:  @tobiasdiez @dimpase @jhpalmieri

Component: **build**

Author: **Matthias Koeppe**

Branch: **[`ad9402f`](https://github.com/sagemath/sagetrac-mirror/commit/ad9402f606204d6dd9a454b9b055bed63247d97a)**

Reviewer: **Dima Pasechnik**

_Issue created by migration from https://trac.sagemath.org/ticket/30780_

