Fix : Add a process to fetch the mime type from the file name for signed url in remote_url #10872 version2

[kitotakumi]

Summary

• Fixes #10737

• This is the modified code as per the comment I received from laipz8200 on This pull request.

• Remove the process of guessing mime type from url

Tip

Close issue syntax: Fixes #<issue number> or Resolves #<issue number>, see documentation for more details.

Screenshots

Before:	After:
...	...

Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[laipz8200]

Thanks!