refactor: remove basic init from js modal

[alexbarnsley]

Summary

https://app.clickup.com/t/863h8wx7b

The failover init causes issues with accessing $refs.modal if the Modal instance is instantiated higher up in a parent. This caused an error in devtools.

Potentially a breaking change if anything still relied on the basic init

Checklist

• I checked my UI changes against the design and there are no notable differences
• I checked my UI changes for any responsiveness issues
• I checked my (code) changes for obvious issues, debug statements and commented code
• I provided a screenshot of my changes to the component (if applicable)
• I regenerated the icons.html file and checked if my newly added icon is shown correctly (if necessary)
• I added an explanation on how to use the component to the readme (if necessary)
• Documentation (if necessary)
• Tests (if necessary)
• Ready to be merged