Mattermost-server: Write an automated test using Cypress for "Replying to an older bot post that has some attachment pretext before the message attachment"

[saturninoabril]

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Notes: Jira ticket

__Test Key: M16734 - Replying to an older bot post that has some attachment pretext before the message attachment__
__Test Group: Messaging__

__Steps:__

1. Create a bot and post a message in a channel. Posted message is in a form of message attachment which is similar to how the Jira plugin posts in ~Bugs channel, that is at least one day old (and has had subsequent messages posted after it in the channel). See cy.task('postMessageAs', {...}) on how to post message as if it’s posted in the past.
2. Click "reply" from [...] menu to reply to a message
3. In right hand sidebar, make a reply post
4. Send and verify reply appears
5. Close the RHS / go back to center channel view

__Expected:__
After 5) you should see "Commented on [bot]’s message: Attachment pretext" on the line below your username on the post showing at the bottom of the center channel, e.g. "Commented on Jira's message: [username] created Bug MM-XXXXX"
See our end-to-end testing documentation for reference - https://developers.mattermost.com/contribute/webapp/end-to-end-tests/

[lawikip]

I will take this one.

[lawikip]

This can be closed

[saturninoabril]

Thanks @lawikip for looking and thank you for your contribution!