LU-14361 statahead: add connect flag check for batch RPC

LU-14361 statahead: add connect flag check for batch RPC

The tests (sanity/test_123 test case series) are all failing for
servers that do not have batch RPC support.
In this patch we add the connect feature flag check in
mdc.*.import for batch RPC support and skip the batch stat-ahead
tests without this support.

Test-Parameters: trivial
Signed-off-by: Qian Yingjin <qian@ddn.com>
Change-Id: I54c95722df803131727e5882156570c9da5293ee
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/54275
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>