ci: Increase rust.debuginfo-level-tests to 2 in **x86_64-gnu-debug**

Simply to increase the scope of the testing.

Author: Enselic

src/ci/docker/host-x86_64/x86_64-gnu-debug/Dockerfile

@@ -38,7 +38,7 @@ ENV RUST_CONFIGURE_ARGS \
       --build=x86_64-unknown-linux-gnu \
       --enable-debug \
       --enable-lld \
-      --set rust.debuginfo-level-tests=1 \
+      --set rust.debuginfo-level-tests=2 \
       --set llvm.use-linker=lld \
       --set target.x86_64-unknown-linux-gnu.linker=clang \
       --set target.x86_64-unknown-linux-gnu.cc=clang \