Remove libexecinfo-dev dependency from perf-test Dockerfile

[whabanks]

Summary | Résumé

This PR removes libexecinfo-dev from the perf-test dockerfile. libexecinfo exposes backtrace() for debugging, which we may not need for the perf tests. A little background:
glibc based systems have this built in by default, musl based systems like Alpine do not include backtrace() by default, hence libexecinfo is available when needed.

We don't appear to use this in other CI related Dockerfiles. It's presence is causing issues in CI currently.

Test instructions | Instructions pour tester la modification

• tests-perf/ops/Dockerfile builds locally.
• CI passes once merged.

Release Instructions | Instructions pour le déploiement

None.

Reviewer checklist | Liste de vérification du réviseur

• This PR does not break existing functionality.
• This PR does not violate GCNotify's privacy policies.
• This PR does not raise new security concerns. Refer to our GC Notify Risk Register document on our Google drive.
• This PR does not significantly alter performance.
• Additional required documentation resulting of these changes is covered (such as the README, setup instructions, a related ADR or the technical documentation).

⚠ If boxes cannot be checked off before merging the PR, they should be moved to the "Release Instructions" section with appropriate steps required to verify before release. For example, changes to celery code may require tests on staging to verify that performance has not been affected.