LU-10465 lov: increase default stripe size to 4MB

LU-10465 lov: increase default stripe size to 4MB

Increase the default stripe size from 1MB to 4MB for better
performance and reduced LDLM lock contention for larger writes.

This can also reduce the need to cache data on the client on a
striped file before a full RPC is generated, since the default
RPC size is 4MB, but with 1MB stripe size, the file would need
4x full stripe_count * stripe_size writes before an RPC is full.

Patch includes several test fixes:
- sanity-pfl: takes into account stripe size in some tests
- sanity-flr: use bigger component size and amount of data to
  saturate all stripes as expected by test
- sanity: 130g to use 1M stripe prior FIEMAP calcs
- sanity-lfsck: 36[a-c] to use 1M stripe as expected by calcs

Test-Parameters: testlist=sanity-compr
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I3cef8805247fc5253e0a0ac05157b9d609054df9
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/37318
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>