Fix Debian packaging JNI shlibdeps failure

[shrec]

What

• Fixed the Linux packaging workflow so native .deb and .rpm jobs no longer build Java JNI artifacts.
• This removes libufsecp_jni.so from the package graph, which was the only object causing dpkg-shlibdeps to fail on amd64.
• The change is workflow-scoped only, so normal JNI builds in CI remain untouched.

Numbers

• Previous failing path: build-deb (amd64) died in cpack -G DEB because dpkg-shlibdeps could not resolve libufsecp.so.3 for libufsecp_jni.so.
• Local repro after the fix: cpack -G DEB now generates ultrafastsecp256k1_3.4.0_amd64.deb successfully.

How to get it

• Branch: dev
• Commit: 94d2bc10