doc: remove .github/ISSUE_TEMPLATE.md in favor of the template folder
This removes the obsolete issue template file since we already have the issue template folder which is the one currently in effect.
Refs: https://github.com/nodejs/node/pull/31611
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines