Commit prefix for merge commit

**Is your feature request related to a problem? Please describe.**

The remote I work with has a requirement to have a ticket ID in the commit title. For that purpose I use commit prefix feature.

However, when a I merge one branch into another with a merge commit, the merge commit uses default message "merged X into Y".

To fix that I need to go to the browser, copy ticket number, then edit the last commit message manually. This is inconvenient.

**Describe the solution you'd like**

I would like so that when I do a merge in lazygit, the merge commit message would automatically add the prefix I configured in the lazygit settings.

**Describe alternatives you've considered**

None.

**Additional context**

None.