chore(core): storybook code styles

[coryrylan]

PR Checklist

Please check if your PR fulfills the following requirements:

• [ ] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been added / updated (for bug fixes / features)
• [ ] If applicable, have a visual design approval

PR Type

What kind of change does this PR introduce?

• [ ] Bugfix
• [ ] Feature
• [ ] Code style update (formatting, local variables)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [x] Documentation content changes
• [ ] clarity.design website / infrastructure changes
• [ ] Other... Please describe:

What is the current behavior?

• Formatting on code example in storybook were slightly off as well as missing a background color
• Modal had edge case of scroll check happening before first render causing an exception in storybook

closes https://github.com/vmware/clarity/issues/6623

What is the new behavior?

• Code snippets now have a background color and excess whitespace is removed
• Modal waits until after first render before checking scroll logic

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

[ashleyryan]

What caused this to break? A dependency update?

[coryrylan]

@ashleyryan yeah this was from earlier this week when I bumped all the Core dependencies. For some reason storybook has different code format logic for the code that is inline in the markdown vs the code that is rendered in the story functions which is why I missed it in the earlier PR