[LU-18680] Improve syntaxes for some nodemap lproc entries

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.17.0
• Severity: 3
• Assignee: Aurelien Degremont
• Reporter: Aurelien Degremont

Description

idmap, exports and ranges are nodemap related entries visible with get_param of nodemap_info. There are all list of elements, with a YAML syntax.

There are 2 issues:

1. There is a syntax bug in 'idmap' when only gid or projid is set, but not uid mapping.
2. When the list is empty, the output is on 3 lines, with a blank one, instead of a more simple '[]'

Let's fix that.