feat(ui): hide sdxl from linear UI (#3815)

## What type of PR is this? (check all applicable)

- [ ] Refactor
- [x] Feature
- [ ] Bug Fix
- [ ] Optimization
- [ ] Documentation Update


## Have you discussed this change with the InvokeAI team?
- [x] Yes
- [ ] No, because:

      
## Description

hides sdxl models from linear ui model select. just a hold-me-over

## Related Tickets & Documents

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## QA Instructions, Screenshots, Recordings

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## Added/updated tests?

- [ ] Yes
- [x] No : n/a

## [optional] Are there any post deployment tasks we need to perform?

invokeai/frontend/web/src/features/parameters/components/Parameters/MainModel/ParamMainModelSelect.tsx

@@ -36,7 +36,7 @@ const ParamMainModelSelect = () => {
     const data: SelectItem[] = [];
 
     forEach(mainModels.entities, (model, id) => {
-      if (!model) {
+      if (!model || ['sdxl', 'sdxl-refiner'].includes(model.base_model)) {
         return;
       }