Perform nightly builds on only specific branches

my organization recently updated out jenkins instance and have been trying to move to jenkinsfile pipelines from freestyle projects. We are wanting to use multibranch pipelines so all our teams can have their project already available in the jenkins interface. The issue is that the project we are wanting to convert currently has a lot of branches (like 100+) as there are various one-off builds we have to do. At this same time we are wanting to build the branch associated with the current sprint nightly (and ONLY this branch). I created a jenkinsfile in the project that looks like the following

// Only perform nightly build on current sprint trunk
String cron_string = BRANCH_NAME == 'branches/sprint-### ? '@midnight' : ''

pipeline {
    agent any
    triggers {

    stages {
        stage('Force fail') {
            steps {
                error "Ran on branch ${env.BRANCH_NAME}"

Now we want each branch to be able to contain it’s own jenkinsfile but some of the settings (like nightly building) would be something we wouldn’t want to get replicated in the creation of new branches and traditionally would be done in the jenkins UI for that reason. With multi-branch pipelines it seems the option to adjust the trigger settings per branch isn’t available. Am I missing something?