Not getting correct page count when replacing an image attachment of a .msg file

When replacing an image attachment (jpg, png, etc.) with a pdf file, the system is not picking up page count of the new pdf file if page count is different from the original image file.

How to reproduce (can be reproduced on all env):
1. Upload a .msg file with image attachments
2. Replace one of the image attachment with a pdf file (different page count)
3. Check redaction app

Sample request on test marshal:
EDU-2023-1025001
https://test-reviewer-web-marshal.apps.silver.devops.gov.bc.ca/foi/712

Screen shot:
[Private Zenhub Image](https://api.zenhub.com/attachedFiles/eyJfcmFpbHMiOnsibWVzc2FnZSI6IkJBaHBBNjN2QVE9PSIsImV4cCI6bnVsbCwicHVyIjoiYmxvYl9pZCJ9fQ==--8d899de89603a87c4da3ac02e272c7023eb05529/replacing%20an%20image%20attachment.png)

Reproduce the replacement flow using the sample request EDU-2023-1025001 and the linked test marshal environment, then trace how replacing an image attachment in a .msg file is reflected in the redaction app. The work is done when the app reports the replacement PDF's page count, including when it differs from the original image.

Written by the indexing model from the issue text.