IDE-304 Remove deprecated upload UI, services, and network logic

[sagar-h007]

Removed deprecated upload-related code including unused UI elements, services, and network logic. This cleanup simplifies the codebase and removes obsolete functionality that is no longer supported.

Jira ticket: https://catrobat.atlassian.net/browse/IDE-304

✅ Include the name of the Jira ticket in the PR’s title
✅ Include a summary of the changes plus the relevant context
✅ Choose the proper base branch (develop)
✅ Confirm that the changes follow the project’s coding guidelines
✅ Verify that the changes generate no compiler or linter warnings
✅ Perform a self-review of the changes
✅ Verify to commit no other files than the intentionally changed ones
⬜ Include reasonable and readable tests verifying the added or changed behavior
⬜ Confirm that new and existing unit tests pass locally
✅ Check that the commits’ message style matches the project’s guideline
✅ Stick to the project’s gitflow workflow
✅ Verify that your changes do not have any conflicts with the base branch
⬜ After the PR, verify that all CI checks have passed
⬜ Post a message in the catroid-stage or catroid-ide Slack channel and ask for a code reviewer

[sonarqubecloud]

Quality Gate passed

Issues
4 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud