gh-131372: Include LDVERSION and EXE in base_interpreter value (#142256)

* Include LDVERSION and EXE in base_interpreter value

In Fedora, build-details.json created and installed for python3.14t
contains "/usr/bin/python3.14" as the base_interpreter value.
Create a correct string, taking into account both LDVERSION and EXE
config variables, similarly to how it's defined in altbininstall in Makefile.

* Add news

Signed-off-by: Filipe Laíns <lains@riseup.net>

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Signed-off-by: Filipe Laíns <lains@riseup.net>
Co-authored-by: Filipe Laíns <lains@riseup.net>