Update the FSFS revprop pack tests to reflect the recent packing
granularity changes.

* subversion/tests/libsvn_fs_fs/fs-fs-pack-test.c
  (get_set_large_revprop_packed_fs): Reduce the numbers by roughly 16
                                     to create the same file splitting
                                     effects as before.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1634935 13f79535-47bb-0310-9956-ffa450edef68