Update expected columns in participant-level-results.tsv based on new session-level data model

[alyssadai]

Description

Column names and descriptions should match the new session-level API response.

See also:

• https://github.com/neurobagel/api/pull/282

Relevant documentation pages

• https://neurobagel.org/query_tool/#participant-level-results

Additional details

No response

[surchs]

@rmanaem