CI/CD & Merges: Enable fast forward merges

Currently the correct process for a simple change is:

• Commit to master
• Merge to beta
• Merge from beta to sucs-site

☑ Generally good practice

☑ Bigger changes can be reviewed in beta easily

🚫 Simple changes generate multiple merge commits

Is there any particular downside to enabling fast-forward merges through Gitlab? The only one I can think of (and haven't checked) is that it might require a one-off rebase of beta and sucs-site to tidy up the current history before it would be useful.