Remove hotUpdateChunkFilename config option workaround

What does this MR do?

After changing branches this problem occurs regularly

@nicksellen had an idea in Slack wich seems to work:

here's an idea: try removing the config option from client/webpack.config.js:
hotUpdateChunkFilename: '[hash].hot-update.js'
it was originally added because of a possible bug in webpack (the issue is linked in the config file).
... but that was a year ago, so maybe is fixed now.
and the default for the hot-update filename includes an [id] in it too... so maybe that makes it unique again...

This MR contains this change

How confident are you it won't break things if deployed?

We found out in Slack that it seems to work

Links to related issues

Checklist

• added a test, or explain why one is not needed/possible...
• no unrelated changes
• asked someone for a code review
• joined #foodsharing-beta channel at https://slackin.yunity.org
• added an entry to CHANGELOG.md (description, merge request link, username(s))
• Once your MR has been merged, you are responsible to update the #foodsharing-beta Slack channel about what has been changed here. They will test your work in different browsers, roles or other settings