Bump default PVC size to 10Gi by default both per-user and per-workspace

[ibuziuk]

Need to bump per-workspace default PVC size from 5 to 10 Gi, due to JetBrains editors resource req:

In addition to the recommendations for calculating xref:administration-guide:calculating-che-resource-requirements.adoc[memory and CPU], make sure you have sufficient PVC size to download and unpack the JetBrains IDE. For reference, CLion IDE, which is the largest of the IDEs, requires approximately 8.5 GB of disk space.

related docs PR eclipse-che/che-docs#2961

[rohanKanojia]

Closed by devfile/devworkspace-operator#1514