install.sh incorrectly pulls from singularity.opensciencegrid.org instead of eic.opensciencegrid.org

### Environment: (where does this bug occur, have you tried other environments)
- Branch: main
- Version: HEAD (latest)
- OS/System: Arch Linux, Linux x86_64, tested on local workstation with CernVM-FS version 2.13.3 & Linux automount version 5.1.9 from AUR
- Special software: N/A
- CVMFS repos: `oasis.opensciencegrid.org`, `eic.opensciencegrid.org`
- CVMFS path tested: `/cvmfs/eic.opensciencegrid.org/singularity/eicweb/`

### Steps to reproduce: (give a step by step account of how to trigger the bug)
1. Run `curl -L https://github.com/eic/eic-shell/raw/main/install.sh | bash`
2. Observe that `install.sh` tries to use `singularity.opensciencegrid.org `and fails:
`athavan@amadeus ~/Documents $ curl -L https://github.com/eic/eic-shell/raw/main/install.sh | bash
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 0
100 15235 100 15235 0 0 33092 0 0
~/Documents ~/Documents
Setting up development environment for eicweb/eic_xl:nightly
- Detected OS: Linux
- Detected CPU: x86_64
- Found singularity at /usr/bin/singularity
`

### Expected Result: (what do you expect when you execute the steps above)
- The installer downloads the container from the EIC CVMFS repository: `/cvmfs/eic.opensciencegrid.org/singularity/eicweb/`
- No reference to `singularity.opensciencegrid.org`
- Container installed successfully

### Actual Result: (what do you get when you execute the steps above)
- Script attempts to pull from `singularity.opensciencegrid.org`
- Fails to execute

### Debug/Workaround:
1. Ensure `singularity.opensciencegrid.org `is not mounted:
`systemctl status autofs`
2. Download `install.sh`
`curl -L https://github.com/eic/eic-shell/raw/main/install.sh -o install.sh`
3. In`install.sh`:
- replace all mentions of `singularity.opensciencegrid.org` to `eic.opensciencegrid.org`
- replace `ORGANIZATION="eicweb"` with `ORGANIZATION="singularity/eicweb"`
4. Run the installer `./install.sh`

Note there are no `.sif` files before `25.12.0` in `/cvmfs/eic.opensciencegrid.org/singularity/eicweb/ ` may be intentional.