Fix Aachen turbine test case

[jblueh]

Proposed Changes

This PR is for fixing #2276.

With the observations in #2276 and after discussion with @joshkellyjak, the fix proposed in #2246 is probably the correct one.

Related Work

#2158, #2246, #2260

PR Checklist

• I am submitting my contribution to the develop branch.
• My contribution generates no new compiler warnings (try with --warnlevel=3 when using meson).
• My contribution is commented and consistent with SU2 style (https://su2code.github.io/docs_v7/Style-Guide/).
• I used the pre-commit hook to prevent dirty commits and used pre-commit run --all to format old commits.
• I have added a test case that demonstrates my contribution, if necessary.
• I have updated appropriate documentation (Tutorials, Docs Page, config_template.cpp), if necessary.

[bigfooted]

LGTM

[joshkellyjak]

Uploading these here for future reference. The fix for the address sanitiser results in a slight change in the values calculated at the shroud during the averaging process in the mixing plane when using linear interpolation.

Base is without fix, modified is with fix.