fix: select the inner modal body css

Summary

select the inner modal body CSS after carbon 10 upgrade. Earlier modal-content was direct child of modal-container now we have one more level. modal-container --> modal-container-body --> modal-content

Change List (commits, features, bugs, etc)

Acceptance Test (how to verify the PR)

Regression Test (how to make sure this PR doesn't break old functionality)

Things to look for during review

[ ] Make sure all references to iot or bx class prefix is using the prefix variable
[ ] (React) All major areas have a data-testid attribute. New test ids should have test written to ensure they are not changed or removed.
[ ] UI should be checked in RTL mode to ensure the proper handling of layout and text.
[ ] All strings should be translatable.
[ ] The code should pass a11y scans (The storybook a11y knob should show no violations). New components should have a11y test written.
[ ] Unit test should be written and should have a coverage of 90% or higher in all areas.
[ ] All components should be passing visual regression test. For new styles or components either a visual regression test should be written for all permutations or the base image updated.
[ ] Changes or new components should either write new or update existing documentation.
[ ] PR should link and close out an existing issue

Name	Link
Latest commit	4607d6eb87e2b596fc15303598395a42d4f7a6e5
Latest deploy log	https://app.netlify.com/sites/carbon-addons-iot-react/deploys/66bf10285d884d0008e2f1dd
Deploy Preview	https://deploy-preview-3878--carbon-addons-iot-react.netlify.app
Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

carbon-design-system / carbon-addons-iot-react