Matomo is downloading even when it's disabled / not used.

[tdonohue]

Describe the bug

This only impacts main / pre-9.0. When Matomo is disabled (matomo.enabled=false on backend), the User Interface will still attempt to download the matomo.js file. This should not occur as matomo.js is unneeded when Matomo is disabled.

To Reproduce

Steps to reproduce the behavior:

1. Disable Matomo on the backend (matomo.enabled=false). This is the default value
2. Start the frontend and open up your DevTools to the "Network" tab (so that you can see the requests sent by the User Interface)
3. Open the homepage (http://localhost:4000)
4. In the Network tab, you'll see that a request to matomo.js will be included. It will likely appear in red with a response of "ERR_CONNECTION_REFUSED"

This behavior can also be seen on https://sandbox.dspace.org as Matomo is disabled there.

Expected behavior

Matomo.js should not be downloaded when Matomo is disable.

Related work

Related to #4018 and #4122