Remove double scroll bar on expanded modal

[millicentachieng]

Describe the bug
There is a double and at times triple vertical scroll bar on expanded modal

To Reproduce
Steps to reproduce the behavior:

1. Go to https://developer.microsoft.com/en-us/graph/graph-explorer
2. Click on Code snippets tab
3. Click on Expand to show the contents of the code snippets tab in a bigger view
4. Notice multiple vertical scroll bars and an unnecessary horizontal scroll bar

Expected behavior
A single scroll bars only if necessary.

Screenshots