[Notification Agent] [Slack] Shorten and cleaner message

[phuongnguyen1204]

Is your feature request related to a problem?

No response

What is your feature request?

• We dont need "See more" because of short summary, just fully display it.
• "View Details" should be removed and the label "Plex Web" should be replaced by "Watch now".
• Minor issue: Can we remove file size of poster as well? :D

I love Tautulli so much, hope i can help to enhance it better :) Thanks developers.

Are there any workarounds?

No response

Additional Context

No response