Update issue template

[mtrezza]

New Issue Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.
• I can reproduce the issue with the latest version of Parse Server.

Issue Description

• Issue templates not uniform across repos.

• Removing "Failing Test Case / Pull Request" section from issue template, because Parse Issue Bot now dynamically suggests to make a PR:

  Failing Test Case / Pull Request

  • 🤩 I submitted a PR with a fix and a test case.
  • 🧐 I submitted a PR with a failing test case.