LU-1561 tests: Fix ALWAYS_EXCEPT in mds-survey.sh

LU-1561 tests: Fix ALWAYS_EXCEPT in mds-survey.sh

Modifying the ALWAYS_EXCEPT assignment in mds-survey.sh does not take
effect, because the test filters have already been built.  This patch
moves the build_test_filter() call below the ALWAYS_EXCEPT assignment.
Also moved downward is the check_and_setup_lustre() call, which
usually goes after environment checks.

Test-Parameters: testlist=mds-survey
Change-Id: I547310e4fccfaaa4fbe7010e14baefa2ab9bbdd4
Signed-off-by: Li Wei <liwei@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/3183
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Yu Jian <yujian@whamcloud.com>
Reviewed-by: wangdi <di.wang@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>