Refactored and changed time range for store fetch warning mails

Touches #9 (closed) #232 (closed) #648 (closed)

What does this MR do?

I just changed some things to better understand the store fetch warning mails which need to be fixed soon in #232 (closed) #648 (closed).
I changed the timerange from - to:

• today 15:00 till tomorrow 15:00
• now till tomorrow at 23:59:59
• Check http://localhost:18084/#/ for mails

Other than that I changed some method and var names and kicked out some code

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

Quite

Links to related issues

How to test

Steps a reviewer can take to verify that this MR does what it says it does e.g.

1. Checkout branch locally
2. Login as store manager
3. create a store with an completely empty pickup time in an hour
4. Execute: ./scripts/docker-compose run --rm --no-deps app php -f run.php Maintenance warnings

Screenshots

• none (backend change)

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