pgo: remove the launcher profile after stage 1
The instrumented launcher emits an empty default.profraw while building the sysimage. Remove that file before stamping stage 1 so it does not dirty the source tree or enter a binary distribution.
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: OpenAI Codex <codex@openai.com>
