#6143 test: add standalone forwardRef regression

[satanTime]

Summary

• add regression coverage for the standalone forwardRef parent/child cycle from Bug: RangeError: Maximum call stack size exceeded when encountering circular reference in component imported using forwardRef #6143
• keep the change test-only on current main
• gate the spec so legacy Angular lanes no-op instead of changing library behavior

Historical verification

• the same spec passes on the report-time main commit ec28e3d412a5605420dddb9eeb9ff5f2f28649c3
• the same spec fails on the reporter's v14.7.1 with RangeError: Maximum call stack size exceeded

Validation

• COMPOSE_PROJECT_NAME=ngmocks_6143_test_132016 sh test.sh coverage
• COMPOSE_PROJECT_NAME=ngmocks_6143_test_132016 sh test.sh a5es5
• COMPOSE_PROJECT_NAME=ngmocks_6143_test_132016 docker compose run --rm a14 npm run test:jasmine:es2015 -- --include src/test/tests/issue-6143/test.spec.ts
• COMPOSE_PROJECT_NAME=ngmocks_6143_test_132016 docker compose run --rm a14 npm run test:jest:es2015 -- --runTestsByPath src/test/tests/issue-6143/test.spec.ts
• COMPOSE_PROJECT_NAME=ngmocks_6143_test_132016 docker compose run --rm a15 npm run test:jasmine -- --include src/test/tests/issue-6143/test.spec.ts
• COMPOSE_PROJECT_NAME=ngmocks_6143_test_132016 docker compose run --rm a15 npm run test:jest -- --runTestsByPath src/test/tests/issue-6143/test.spec.ts
• COMPOSE_PROJECT_NAME=ngmocks_6143_test_132016 docker compose run --rm a20 npm run test:jasmine -- --include src/test/tests/issue-6143/test.spec.ts
• COMPOSE_PROJECT_NAME=ngmocks_6143_test_132016 docker compose run --rm a20 npm run test:jest -- --runTestsByPath src/test/tests/issue-6143/test.spec.ts

Refs #6143

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (c0b8705) to head (aaf029a).
⚠️ Report is 10 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main    #13453   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          228       228           
  Lines         4168      4168           
  Branches      1187      1187           
=========================================
  Hits          4168      4168           

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