lttng-ust dependency on python3

A dependency to python3 was added to lttng-ust in https://git.alpinelinux.org/aports/commit/main/lttng-ust/APKBUILD?h=3.12-stable&id=54f01ae9e06c9cfec585064b86512198f956ff40. This was introduced in Alpine 3.12. When compared to Alpine 3.11, installing the lttng-ust package increases the installation size by a factor of 40 (1.1 MB in Alpine 3.11 vs 44.4 MB in Alpine 3.12).

I heard that python3 is an optional dependency that's only needed if invoking the lttng-gen-tp script. Since the addition of python3 has such a huge impact on the installation size, I think it should not be included by default. Possibly, the package should be refactored so that only a sub-package has this dependency.