build-unit-test-docker: Run ldconfig

The preinstalled packages are copied to /usr/local but ld is not aware
of these libraries until ldconfig is run. This makes the container more
useful for interactive use out of the box.

Tested:
== Before ==
docker$ ldd /usr/local/lib/libboost_coroutine.so | grep 'not found'
        libboost_context.so.1.84.0 => not found

== After ==
docker$ ldd /usr/local/lib/libboost_coroutine.so | grep 'not found'
docker$

Change-Id: I3f6508ad6068df03206b6c405532c0230dd95d8d
Signed-off-by: Jonathan Doman <jonathan.doman@intel.com>
diff --git a/scripts/build-unit-test-docker b/scripts/build-unit-test-docker
index 44c3a8a..8f8157a 100755
--- a/scripts/build-unit-test-docker
+++ b/scripts/build-unit-test-docker
@@ -912,6 +912,9 @@
 # and data installs
 RUN chown -R {username}:{username} /usr/local/share
 
+# Update library cache
+RUN ldconfig
+
 {proxy_cmd}
 
 RUN /bin/bash