Remove test libs from release package

[bmatican]

Quick listing through our release package:

ls -Slr lib/yb/* | grep -i test
3:-rwxr-xr-x. 1 bogdan ybdev 275000 Feb 28 01:18 lib/yb/libyb_test_main.so
7:-rwxr-xr-x. 1 bogdan ybdev 477120 Feb 28 01:18 lib/yb/libyb_test_util.so
32:-rwxr-xr-x. 1 bogdan ybdev 1995496 Feb 28 01:18 lib/yb/libyb-redisserver-test.so
34:-rwxr-xr-x. 1 bogdan ybdev 2196288 Feb 28 01:18 lib/yb/libyb_client_test_util.so
44:-rwxr-xr-x. 1 bogdan ybdev 4143104 Feb 28 01:18 lib/yb/libtablet_test_util.so
47:-rwxr-xr-x. 1 bogdan ybdev 4423192 Feb 28 01:18 lib/yb/libtserver_test_util.so
63:-rwxr-xr-x. 1 bogdan ybdev 19864736 Feb 28 01:18 lib/yb/libintegration-tests.so

Lower amount of total size, but still not needed in the release.

cc @mbautin @ttyusupov