build-unit-test-docker: chown: be more specific

The chown step has shown to take a significant amount of time compared
to other parts of the CI docker image build. Be a bit more granular with
it as the only real need was to ensure other repos could install
generated files under /usr/local/share/

Tested:
- Verified that I could run the script using different user id's
  on the same system against repos that install into /usr/local/share.

Change-Id: I61e43241604f48d66c4e8ab20cabea91eb064bbe
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/scripts/build-unit-test-docker b/scripts/build-unit-test-docker
index 7c95fe3..eed9fbf 100755
--- a/scripts/build-unit-test-docker
+++ b/scripts/build-unit-test-docker
@@ -855,7 +855,7 @@
 
 # Ensure user has ability to write to /usr/local for different tool
 # and data installs
-RUN chown -R {username}:{username} /usr/local
+RUN chown -R {username}:{username} /usr/local/share
 
 {proxy_cmd}