Improve efficiency of upcoming CI action for testing SBML compilation

[reneSchm]

Motivation / Current Behaviour

The CI job recompiles memilio, all models and tests. This should not be necessary, since the only change from the build-cpp-gcc_clang job (providing the build files) is the inclusion of SBML, which should not affect the main library, tests or models.

Enhancement description

Try to avoid recompilation to save on resources and time.

Additional context

https://github.com/SciCompMod/memilio/pull/1235#discussion_r2166502905

Checklist

• [x] Attached labels, especially loc:: or model:: labels.
• [x] Linked to project