Use 'find' instead of 'ls' to create the list of reportings available for shinyresults

[dklein-pik]

🐦 Description of this PR 🐦

Use 'find' instead of 'ls' to create the list of reportings available in the results archive for shinyresults.

Explanation https://www.baeldung.com/linux/argument-list-too-long-error

🔧 Checklist for PR creator 🔧

• Label pull request from the label list.

  • Low risk: Simple bugfixes (missing files, updated documentation, typos) or changes in start or output scripts

• Self-review own code

  • No hard coded numbers and cluster/country/region names.
  • The new code doesn't contain declared but unused parameters or variables.