Fix string "true" not showing in extended metadata

[Arnei]

In the extended metadata tab of the event details, fields with the stirng value "true" or "false" would not render. The fields value could only by checked by clicking into it.

This fixes that by removing a method that, as far as I can tell, is absolutely pointless.

How to test this

To properly test this, an Opencast with extended metadata for either events or series is required. You can find more details on how to configure that here: https://docs.opencast.org/develop/admin/#configuration/metadata/#extended-metadata

[github-actions]

Use docker or podman to test this pull request locally.

Run test server using develop.opencast.org as backend:

podman run --rm -it -p 127.0.0.1:3000:3000 ghcr.io/opencast/opencast-admin-interface:pr-1044

Specify a different backend like stable.opencast.org:

podman run --rm -it -p 127.0.0.1:3000:3000 -e PROXY_TARGET=https://stable.opencast.org ghcr.io/opencast/opencast-admin-interface:pr-1044

It may take a few seconds for the interface to spin up.
It will then be available at http://127.0.0.1:3000.
For more options you can pass on to the proxy, take a look at the README.md.

[github-actions]

This pull request is deployed at test.admin-interface.opencast.org/1044/2025-01-06_16-09-47/ .
It might take a few minutes for it to become available.