Set max text height to prevent overflow (#18862)
Set max text height to prevent overflow (#18862)

Sets a max height for review text boxes to prevent a very annoying bug where users cannot access the "submit" button.

Before:
![image](https://user-images.githubusercontent.com/12700993/155253001-e1dab086-aaf3-4338-889d-6a861728274a.png)

After:
![image](https://user-images.githubusercontent.com/12700993/155253144-5b9a3547-9582-412f-867f-41a45a14a0fe.png)

Interestingly, I don't see this bug on Firefox. 
go-gitea/gitea,go-gitea/gitea,go-gitea/gitea