Jetpack Social: Incorrect `og:image` selection causing failed shares when URL-redirecting plugins are used

### Impacted plugin

Jetpack, Social

### Quick summary

Jetpack Social fails to share on Bluesky (`InvalidMimeType` error) and Tumblr (`400 Bad Request`). The issue appears to be caused by Jetpack Social selecting an incorrect `og:image` URL that redirects to the post itself instead of using the correct image set by Rank Math.

Please refer to internal Slack thread for more details: p1740993403565959/1740992102.027679-slack-C02JJ910CNL

### Steps to reproduce

Key findings:

- The selected image URL redirects to the post, returning a text/html response instead of an image.
- The correct og:image is present in the metadata but is not being used.
- Some plugins may alter image URLs, causing unexpected redirects. In the reported case, the site was using the [BetterLinks plugin](https://wordpress.org/plugins/betterlinks/), which might be modifying the URLs, similar to past cases where plugins redirected images to prevent hotlinking.
- The logs show that Jetpack Social attempts to auto-convert the image but ends up with a text/html response, leading to an InvalidMimeType error on Bluesky.

### Site owner impact

Fewer than 20% of the total website/platform users

### Severity

Minor

### What other impact(s) does this issue have?

No revenue impact

### If a workaround is available, please outline it here.

_No response_

### Platform (Simple and/or Atomic)

_No response_

Start by tracing Jetpack Social's og:image selection and image auto-conversion flow, using the reported Rank Math, BetterLinks, Bluesky, and Tumblr combination to reproduce the failure. Done means the correct image metadata is selected without redirecting to the post, and sharing succeeds on both affected services.

Written by the indexing model from the issue text.