Remove combined issue template

.github/ISSUE_TEMPLATE.md

-## Directions
-
-GitHub Issues are reserved for actionable bug reports and feature requests.
-General questions should be asked at the [InfluxData Community](https://community.influxdata.com) site.
-
-Before opening an issue, search for similar bug reports or feature requests on GitHub Issues.
-If no similar issue can be found, fill out either the "Bug Report" or the "Feature Request" section below.
-Erase the other section and everything on and above this line.
-
-*Please note, the quickest way to fix a bug is to open a Pull Request.*
-
-## Bug report
-
-### Relevant telegraf.conf:
-
-### System info:
-
-[Include Telegraf version, operating system name, and other relevant details]
-
-### Steps to reproduce:
-
-1. ...
-2. ...
-
-### Expected behavior:
-
-### Actual behavior:
-
-### Additional info:
-
-[Include gist of relevant config, logs, etc.]
-
-
-## Feature Request
-
-Opening a feature request kicks off a discussion.
-
-### Proposal:
-
-### Current behavior:
-
-### Desired behavior:
-
-### Use case: [Why is this important (helps with prioritizing requests)]