LU-14139 llite: simplify callback handling for async getattr

LU-14139 llite: simplify callback handling for async getattr

In this patch, it prepares the inode and set lock data directly in
the callback interpret of the intent async getattr RPC request (in
ptlrpcd context), simplifies the old impementation that defer this
work in the statahead thread.

If the statahead entry is a striped directory, it may generate
new RPCs in the ptlrpcd interpret context to obtain the
attributes for slaves of the striped directory:
	@ll_prep_inode()->@lmv_revaildate_slaves()
This is dangerous and may result in deadlock in ptlrpcd interpret
context, thus we use work queue to handle these extra RPCs.
Add sanity 123d to verify that it works correctly.

According to the benchmark result, the workload "ls -l" to a large
directory on a client without any caching (server and client),
containing 1M files (47001 bytes) shows the results with measured
elapsed time:
- w/o patch:	180 seconds;
- w patch:	181 seconds;

There is no any obvious performance regession.

Test-Parameters: testlist=racer,racer,racer
Signed-off-by: Qian Yingjin <qian@ddn.com>
Change-Id: I43aba0f609243f34f7e7b674c7fff5fa417b1c02
Reviewed-on: https://review.whamcloud.com/45648
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>