Manage disk space constraints in continuous integration

[slel]

As suggested in #32001 comment:17, this may help:

https://github.com/easimon/maximize-build-space

CC: @dimpase @mkoeppe @slel

Component: porting

Issue created by migration from https://trac.sagemath.org/ticket/32280

[mkoeppe]

This has been in use for a while.