Release planner shutdown plan

Steps to complete release planner shutdown and remove PowerApps.

Must do before disabling release planner UI: **Target: (05/19/2026)**
- [x] [Update azsdk agent to return link to new dashboard release plan view instead of link to the release planner](https://github.com/Azure/azure-sdk-tools/issues/15628)
- [x] #15629
- [x] #15630

Disable release plan related UI: **Target: (06/08/2026)**
- [x] #15786
- [x] #15784
- [x] #15669
- [x] #15631
- [x] #15632
- [x] #15633
- [x] #15367
- [x] #15835
- [x] #15810
- [x] #15793
- [x] #15867
- [x] #15869

Move service and product details from PowerApps DB to Cosmos DB in Engsys **Target: (6/19/2026)**
- [x] #15634
- [x] #15635
- [x] #15636
- [x] #15637
- [x] #15975
- [x] #15964
- [x] #15800
- [x] #15799

Onboarding services: **Target: 6/26/2026**
- [ ] #15638
- [ ] #15639
- [ ] #15640
- [ ] #15641

Cloud flows: **Target: 6/26/2026**
- [ ] #15642