feat: use generateName for PVCs created by Notebook form

[neo99zhang]

What this PR does

Changes the Jupyter Notebook form to use Kubernetes generateName instead of name when creating new PVCs. This prevents naming conflicts when notebooks are recreated or when PVCs from deleted notebooks still exist.

Why

Currently, PVCs are created with static names like {notebook-name}-volume. If a notebook is deleted but the PVC persists (common with Retain reclaim policies or delayed cleanup), recreating a notebook with the same name fails due to PVC naming conflict.

Using generateName allows Kubernetes to auto-generate unique suffixes, e.g., mynotebook-volume-x7k2m.

Changes

File	Change
shared/utils/volumes/forms.ts	createNewPvcFormGroup(): use generateName instead of name; default name ends with -
form-workspace-volume.component.ts	Update workspace volume name to {notebook-name}-workspace-
form-data-volumes.component.ts	Update data volume name to {notebook-name}-datavol-{n}-

How to test

1. Deploy the updated Jupyter web app
2. Create a new notebook with default volume settings
3. Verify PVC is created with a generated suffix (e.g., mynotebook-workspace-x7k2m)
4. Delete the notebook (keeping the PVC)
5. Create a new notebook with the same name
6. Verify a new PVC is created without conflict

Notes

• The setGenerateNameCtrl helper and generateName handling in createMetadataFormGroupFromPvc already exist, so this change builds on existing infrastructure
• Volume name templates now end with - as required by Kubernetes generateName spec

Closes #842

[google-oss-prow]

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