Drop ` from` and `into` words in `clean-conversation-headers` #4145

Following https://github.com/sindresorhus/refined-github/pull/4103, that line is again longer than it needs to.

What if, we:

• drop into
• replace from with a ⬅ (octicon)

<img width="377" alt="Screen Shot" src="https://user-images.githubusercontent.com/1402241/112181065-b4035b80-8bc1-11eb-8f67-3f0e95114ed3.png">

<img width="328" alt="Screen Shot" src="https://user-images.githubusercontent.com/1402241/112182208-b5815380-8bc2-11eb-94ce-0d8bbc05da7d.png">

In merged PRs we probably need to use a spacer in place of into

<img width="530" alt="Screen Shot" src="https://user-images.githubusercontent.com/1402241/112181718-4a378180-8bc2-11eb-9ea2-97e62d1da917.png">

<img width="500" alt="Screen Shot 1" src="https://user-images.githubusercontent.com/1402241/112182218-b74b1700-8bc2-11eb-966d-a47ced22ea55.png">

Worth the change?

Maybe https://github.com/sindresorhus/refined-github/issues/3863 could be added next to the branch name, so having more room would be beneficial.