279 - Fix remove loading text

[MellyGray]

What this PR does / why we need it:

This PR removes the loading text that appears when accessing the SPA.

Which issue(s) this PR closes:

• Closes 'Loading' text briefly appears when navigating from Home Page to View Dataset Page #279

Special notes for your reviewer:

The loading message was a placeholder for the React Suspense fallback. This fallback exists to give some feedback to the user about the page being loaded but it didn't seem to be necessary since we don't have long loading times and there is already a loading indicator when accessing any SPA page

Check the video to see the loading text appearing:
https://github.com/IQSS/dataverse-frontend/assets/17010447/60c11a1e-6ad3-4827-861c-1655a5ebb651

Suggestions on how to test this:

Step 1: Run the development environment

1. Run npm I
2. cd packages/design-system && npm run build
3. cd ../../
4. Check that you have a .env file such as the .env.example, with the VITE_DATAVERSE_BACKEND_URL=http://localhost:8000 variable
5. cd dev-env
6. ./run-env.sh unstable
7. To check the environment go to http://localhost:8000 and check your local dataverse installation

Step 2: Test Dataset View mode with the implemented changes to download the files

1. Go to http://localhost:8000/spa
2. Check that during the loading of the page, no 'loading' text appears at the top left corner of the page.

Does this PR introduce a user interface change? If mockups are available, please link/include them here:

No

Is there a release notes update needed for this change?:

No

Additional documentation:

[coveralls]

coverage: 97.822%. remained the same
when pulling b81f0d6 on fix/279-loading-text-appears-when-navigating
into c0516c5 on develop.

[M27Mangan]

Works as intended. Good work!

[ekraffmiller]

looks good! Merging