cmake: don't rebuild bundled Boost as unused shared libraries

The bundled-Boost install step ran `b2 install` without the build
features passed to the preceding `b2 ... stage` step. With no `link=`
feature, b2 falls back to its default (link=shared) and recompiles the
entire library set as shared objects on top of the static staged build -
roughly doubling the Boost build - then installs 18 shared libs that
nothing uses: bundled Boost is always static (Boost_USE_STATIC_LIBS is
forced ON for the non-system path, and the imported targets are
STATIC / .a), so only Ceph, Arrow and OpenTelemetry link the .a.

Pass the same features to the install command so it reuses the staged
static build instead of rebuilding. Verified at the b2 level: with the
features, the install step compiles 0 files (vs the full set before) and
installs only .a, no .so.

Signed-off-by: Jusufadis Bakamovic <jusufadis.bakamovic@clyso.com>