fix: L003 Conclusions and Recommendations are empty in some cases

Description

In some cases, Conclusions and Recommendations in L003 appeared to be empty, which was unexpected.

During researсh, I found out that one of the results of !386 (merged) was changing the structure of L003 JSON file. So as a result, L003 JSON data file cannot be loaded for analyzing and generation of recommendations. Structure description of L003 JSON file updated in pghrep util, so analysis returned.

Related issue

https://gitlab.com/postgres-ai/postgres-checkup/issues/438

Examples

[present examples for reviewers: new CLI output, screenshots, etc]