Search and Replace WordPress Code

Using Gutenberg editor and GeneratePress, I have a client who no longer uses Calendly for appointments and uses an iframe for her new appointment management. There are about 150 posts that include the Calendly widget. I have already changed the pattern for future posts. I'm looking for the best way to do this without having to do it manually.

I need to replace:
<!– wp:jetpack/calendly {"url":"https://example.com"} –>

<div class="wp-block-jetpack-calendly"></div>

<!– /wp:jetpack/calendly –>

with:

<!– wp:html –>

<iframe src="https://example.com" title="Make an Appointment" width="100%" height="800px" frameborder="0">

</iframe>

<!– /wp:html –>

Thanks in advance for your help.