LU-10499 statahead: introducing OBD_CONNECT2_BATCH_RPC flag

LU-10499 statahead: introducing OBD_CONNECT2_BATCH_RPC flag

Add a new connection flag OBD_CONNECT2_BATCH_RPC flag for
multi-RPC aggregation.

By necessity, also include definitions for OBD_CONNECT2_REP_MBITS,
OBD_CONNECT2_MODE_CONVERT so obd_connect_names[] works.

Lustre-change: https://review.whamcloud.com/40791
Lustre-commit: 6007dc9382df7260841a4748158307ade25f22ef

Test-Parameters: trivial
Signed-off-by: Qian Yingjin <qian@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Wang Shilong <wshilong@whamcloud.com>
Change-Id: I05369c3ece75119eb3363d05065a0bb929839b4a
Reviewed-on: https://review.whamcloud.com/46107
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>