LU-15060 tests: skip sanity-flr test_208 in interop

LU-15060 tests: skip sanity-flr test_208 in interop

Sanity test_208[ab] check a feature that was only landed in 2.14.55.

Test-Parameters: trivial serverversion=2.14.0 testlist=sanity-flr env=ONLY=208
Fixes: 8507472dd37e ("LU-14996 lov: prefer mirrors on non-rotational OSTs")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I7735582ed9683d686396c14e2a4e254c648f7546
Reviewed-on: https://review.whamcloud.com/46563
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Alena Nikitenko <anikitenko@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>