fix filter bug

[winprn]

Description

Fix a minor bug when using filter of schools' names that have the same prefix

Type of change: bug fix

What

I changed the selected_orgs to an array of schools' names, instead of a concatenated string

How Has This Been Tested?

• Select multiple schools
• Remove schools
• Clear filter

Checklist

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• I have explained the purpose of this PR.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the README/documentation
• Any dependent changes have been merged and published in downstream modules
• Informed of breaking changes, testing and migrations (if applicable).
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By submitting this pull request, I confirm that my contribution is made under the terms of the AGPL-3.0 License.