[CI] zombienet integration tests with shielding target TargetA&B

[brenzi]

this is crucial for regression testing (#1666 would have benefited a lot)

zombienet:

• rococo relay
  • integritee para
  • asset hub para

worker jobs (legit to run against same zombienet in parallel if shards are specified differently might be no good idea though to have potential interference):

• shielding-target Integritee = integritee para (in addition to solochain test)
• shielding-target target_a = rococo relay
• shielding-target target_b = asset hub rococo

[brenzi]

do some asset shielding/unshielding testing at the same time

• shard retirement of assets

[brenzi]

Zombienet is very brittle. It may be beneficial to use pure- rust integration testing instead similar to fellowship runtimes:
See integritee-network/parachain#325 for an example