Increase Default PVC Size to 10Gi for per-workspace

[rohanKanojia]

Description

Related to eclipse-che/che#23590 (per-workspace)

The default PersistentVolumeClaim (PVC) size for DevWorkspaces should be increased from 5Gi to 10Gi to meet the resource requirements of JetBrains IDEs. This change prevents PVC provisioning errors caused by insufficient storage.

Acceptance Criteria

• Default PVC size in the DevWorkspace Operator is 10Gi.
• DevWorkspaces provision successfully without PVC size errors.
• perWorkspace-storage test cases are updated and passing.
• CRDs and devworkspaceoperatorconfig documentation reflect the updated PVC size.
• Validation confirmed on a deployed DevWorkspace Operator (PVC shows 10Gi capacity).

[rohanKanojia]

Closed via #1514