LU-17446 revert: "ldlm: Do not wait for BL AST RPC completion on cancel"

LU-17446 revert: "ldlm: Do not wait for BL AST RPC completion on cancel"

This reverts commit cfd5411db998c2b0427e310a19b8741b1ec3644e.
There can be LASSERT triggered due to blocking callbacks on one lock.
This will be fixed to handle this in a more generic manner.

Change-Id: I5bdd59e3668de0f1db02f3654c73531712a77c72
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/54643
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>