Fix DWDS tests with webdev 2.0.0

[grouma]

DWDS tests make use of webdev by global activation. When webdev 2.0.0 was released it broke the tests. Changes:

• No longer implicitly cancel the stdout stream as that causes issues with webdev
• Get instanceId through an evaluate instead of hard coding a fake one
  • webdev 2.0.0 now embeds one
• Run only one test at a time due to blocking issue build_daemon returns Version skew in a race condition build#2210