chore: Remove erroneous comment about placeholder merges

[bvrooman]

Related issues:

• Ottersec issue 3 about comment described here: https://fuellabs.slack.com/archives/C06P42TQEFL/p1714101628804279

Checklist

• [ ] Breaking changes are clearly marked as such in the PR description and changelog (N/A)
• [ ] New behavior is reflected in tests (N/A)
• [ ] If performance characteristic of an instruction change, update gas costs as well or make a follow-up PR for that (N/A)
• [ ] The specification matches the implemented behavior (link update PR if changes are needed) (N/A)

Before requesting review

• [x] I have reviewed the code myself
• [ ] I have created follow-up issues caused by this PR and linked them here