fix: default selected blueprint sub-generators

[belljinwo-jpg]

Fix #33923

Summary

• Apply default sub-generator configuration when generate-blueprint runs with --defaults.
• Preserve existing --all-priorities behavior while avoiding interactive sub-generator prompts for selected and additional sub-generators.
• Add regression coverage for --defaults --sub-generators app.

Verification

node_modules/.bin/esmocha.cmd generators/generate-blueprint/generator.spec.ts --no-insight --forbid-only

Result: 28 passing, 14 pending.

Notes

This change was prepared with AI assistance and personally reviewed/tested before submission.

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