Remove securityContext privillege from the s2i-java-11-binary task

[mostmark]

When deploying the workshop to OCP 4.7 and using OpenShift Pipelines Operator >=1.4.1 the task s2i-java-11-binary fails with an error message. In the task securityContext: privileged: true entries needs to be removed.

In addition to this the buildah step needs to be modified to use the vfs storage driver (i.e. '--storage-driver=vfs' needs to be added as an agrument)