Use generateName instead of name for PVCs created by Notebook form

### Checks

- [x] I have searched the [existing issues](https://github.com/kubeflow/notebooks/issues).
- [x] My request is related to one of the components in the [`kubeflow/notebooks`](https://github.com/kubeflow/notebooks) repository.

### Motivation

### Problem
When creating a new Notebook, the Jupyter web app creates PersistentVolumeClaims (PVCs) with static names like `{notebook-name}-volume`. This causes issues when:
1. **PVC naming conflicts**: If a user deletes a notebook but the PVC is retained (or deletion is delayed), recreating a notebook with the same name fails because the PVC name already exists.
2. **Orphaned PVC cleanup**: When PVCs have static names tied to notebook names, it's harder to track which PVCs were auto-created vs manually created.

### Benefits
- Eliminates PVC naming conflicts when recreating notebooks
- Better UX for notebook recreation workflows
- Aligns with Kubernetes best practices for dynamically created resources

### Environment
- Kubeflow Notebooks v1
- Affects: `components/crud-web-apps/jupyter/frontend/`

### Implementation

### Proposed Solution
Use Kubernetes `generateName` instead of `name` for PVC metadata when creating new PVCs. This allows Kubernetes to automatically append a unique suffix (e.g., `mynotebook-volume-x7k2m`), preventing naming collisions.
The infrastructure for this partially exists—there's already a `setGenerateNameCtrl` helper function in `volumes/forms.ts` and `createMetadataFormGroupFromPvc` handles `generateName`. However, the default form creation in `createNewPvcFormGroup()` still uses static `name`.

### Changes Required
- `createNewPvcFormGroup()` should use `generateName` with a trailing `-` instead of `name`
- Update default volume name templates to end with `-` (required for `generateName`)
- Update workspace and data volume components to use the new naming pattern

### Are you willing & able to help?

- [x] I am able to submit a PR!
- [x] I can help test the feature!

Start in components/crud-web-apps/jupyter/frontend/volumes/forms.ts, comparing setGenerateNameCtrl, createMetadataFormGroupFromPvc, and createNewPvcFormGroup(). Then inspect the workspace and data volume components for their default name templates. Done means newly created PVC forms use the generated-name pattern consistently and avoid conflicts when notebooks are recreated.

Written by the indexing model from the issue text.