LU-16523 lprocfs: adjust the format of rename_stats

LU-16523 lprocfs: adjust the format of rename_stats

Adjust the format of rename_stats to a more human-friendly YAML.

Lustre-change: https://review.whamcloud.com/49869
Lustre-commit: 73b5d7db7e8d3ede42524fc447fb30fa05ea7a3f

Fixes: bedb797c5d ("LU-16110 lprocfs: make job_stats and rename_stats valid YAML")
Signed-off-by: Lei Feng <flei@whamcloud.com>
Test-Parameters: trivial
Change-Id: I20e6d07c974e907bb2e30412dd1899f845de2021
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/49871
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>