Remove extra line under codeblock

[sobitneupane]

@Beamanator @rushatgabhane will you please review this?

Code block is wrapped by <pre> </pre> tags. And When new line is added <br /> tag is also added. So, In turn, </pre> <br /> tags get added in the html.
Here, </pre> tag changes the line and <br /> add another line. So there is extra line.

Fixed Issues

$ Expensify/App#7496

Tests

1. Send some code blocks in chat like

   Here is come code

   const myLineOfCode = 'some code';
   

   And that was my code!

2. There should not be an extra line below the codeblock.

QA

1. Send some code blocks in chat like

   Here is come code

   const myLineOfCode = 'some code';
   

   And that was my code!

2. There should not be an extra line below the codeblock.

Screenshots

Web

Desktop

Android

IOS

mWeb

[sobitneupane]

Found this issue while working on this PR https://expensify.slack.com/archives/C01GTK53T8Q/p1644507497800049

[rushatgabhane]

This change will be deployed to Expensify/App in the above PR (7700)