This change removes references to Observatory, including:
- Deprecated flags
- Deprecated embedder APIs
- Outdated documentation
- Documentation instances where "VM service" should have been used
- Incorrectly named tests / directories
As a part of this change, `--serve-observatory` is no longer a valid
flag.
Observatory is still available for now via the `_serveObservatory` RPC,
but will be removed in a follow up PR once we've prepared for breakages
in G3.
Work towards https://github.com/dart-lang/sdk/issues/50233
FYI @a-siva
This puts the wiki pages owned by the Tool team into the docs/tool directory as planned in [flutter.dev/go/migrate-flutter-wiki-spreadsheet](https://docs.google.com/spreadsheets/d/1x65189ZBdNiLRygpUYoU08pwvXD4M-Z157c6pm8deGI/edit?usp=sharing)
It also adds the tool team labels to the label bot for future PRs.
Changes to the content were only updating cross links, or link to refer to the main branch rather than master.
Remaining links to the wiki will be updated once all other pages have finished moving, they still work in the meantime.
Part of https://github.com/flutter/flutter/issues/145009
