Rails: Remove support for VS Code(fork) 1.81

MR: Remove support for VS Code(fork) 1.81 (!149182 - merged)

Description

As a followup to Rails: Make VS Code(fork) 1.85 as default (#440292 - closed) , users should no longer be able to switch to old version of VS Code(fork) 1.81 using the attributes in their devfile.

Acceptance Criteria

• Setting the attribute does not have any impact on the VS Code(fork) being injected into the workspace.