eclipse/che-theia:next still contains @theia/cpp extension

[tolusha]

Describe the bug

eclipse/che-theia:next still contains @theia/cpp extension that was excluded in this commit [1]

[1] eclipse-che/che-theia@992a059

Steps to reproduce

1. docker pull eclipse/che-theia:next
2. go into the container

$ ls /home/theia/node_modules/@theia/ | grep cpp
> cpp

Expected behavior

@theia/cpp extension shouldn't be present

Additional context

eclipse/che-theia:latest - doesn't contain the extension
if build eclipse/che-theia:next locally then @theia/cpp doesn't exist either

Is needed for

#13698

[tsmaeder]

Raising priority: we can't release cpp support without this.

[benoitf]

the issue is that the PR can't be merged as happy path is failing to unrelated issues
eclipse-che/che-theia#441

[benoitf]

eclipse-che/che-theia#449 should unblock

[mmorhun]

Done