Drop ADTypes QA v1 SciMLTesting compat

[ChrisRackauckas-Claude]

Ignore until reviewed by @ChrisRackauckas.

Summary

• Drop the remaining v1 SciMLTesting compat allowance from ADTypes root and QA environments.
• Keep both environments on SciMLTesting = "2.1", which resolved locally to SciMLTesting v2.2.0.

Validation

• git diff --check
• julia +1.10 -e 'using Runic; exit(Runic.main(ARGS))' -- --check .\n- TOML assertion that root and QA SciMLTesting compats are exactly "2.1"\n- GROUP=Core julia +1.10 --project=. -e 'using Pkg; Pkg.instantiate(); Pkg.test(; coverage=false)'\n- GROUP=QA julia +1.10 --project=. -e 'using Pkg; Pkg.instantiate(); Pkg.test(; coverage=false)'

[ChrisRackauckas-Claude]

Closing after the fresh General-registry audit corrected the premise: SciMLTesting v1 was registered on 2026-06-13 and v2 on 2026-07-11. The v1 line is only one month old and must remain supported during this transition; removing it as stale would be premature. This PR contains no independent change worth retaining.