addon-storysource copy line numbers in chrome

[iriswang233]

Describe the bug
When copying code from story tab in chrome and paste it in vs code, line numbers will be pasted too. This is not user friendly. However, when copying code from story tab in firefox and paste it in vs code, line numbers are not there. This should be the correct behaviour.
To Reproduce

1. open https://backstage.io/storybook/?path=/story/layout-item-cards--styling in chrome
2. open story tab
3. copy several lines code
4. paste in vs code file => Line numbers are pasted

System
chrome
Additional context
no

[shilman]

ZOMG!! I just released https://github.com/storybookjs/storybook/releases/tag/v7.0.0-alpha.24 containing PR #18725 that references this issue. Upgrade today to the @future NPM tag to try it out!

npx sb upgrade --prerelease

Closing this issue. Please re-open if you think there's still more to do.