docs: Cleanup issue templates

.github/ISSUE_TEMPLATE/Compile_results_are_incorrect.md

-<!--
-When encountering a syntax, or compilation issue:
-
-- Please note that we cannot backport fixes to old versions, so ensure that you are running the latest release https://github.com/sass/node-sass/releases
-- Search for duplicate or closed issues https://github.com/sass/node-sass/issues?utf8=%E2%9C%93&q=is%3Aissue
-- Validate with http://sassmeister.com/ that the code works with Ruby Sass, then open an issue on `LibSass` https://github.com/sass/LibSass/issues/new
-
-Sorry you didn't have the experience you expected.
-
--->

.github/ISSUE_TEMPLATE/Installation_Problem.md

-<!--
-
-Before opening an issue:
-
-- Check that the version of node-sass you're trying to install supports your version of Node by looking at the release page for that version https://github.com/sass/node-sass/releases
-- If you're running the latest verions of Node, you'll likely need the latest node-sass, we don't backport support to old versions of node-sass
-- Read the common workarounds in https://github.com/sass/node-sass/blob/master/TROUBLESHOOTING.md
-
-**When reporting an bug, YOU MUST PROVIDE THE FOLLOWING INFORMATION
-or your issue will be closed without discussion**
--->
-
-- NPM version (`npm -v`):
-- Node version (`node -v`):
-- Node Process (`node -p process.versions`):
-- Node Platform (`node -p process.platform`):
-- Node architecture (`node -p process.arch`):
-- node-sass version (`node -p "require('node-sass').info"`):
-- npm node-sass versions (`npm ls node-sass`):

.github/ISSUE_TEMPLATE/Request_Security.md

-# Please do not open an issue
-
-See https://github.com/sass/node-sass/issues/2355 for the reason we can't upgrade the Request version that your security scanner is flagging.