Adjust bug template to adhere to standard bug report format

* https://developer.mozilla.org/en-US/docs/Mozilla/QA/Bug_writing_guidelines
* Guidelines use the following format

- Summary
- Steps to Reproduce
- Expected Behaviour
- Actual Behaviour

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gitlab-org/gitlab-ce/issues/14905#note_12235996

This reverts commit 3e991230.

# Conflicts:
#	app/models/project.rb

Signed-off-by: Rémy Coutable <remy@rymai.me>

Now that we autoscale runner, we don't need to optimize for their usage
anymore. Abusing of "ci skip", for instance for view changes can lead to
broken specs, so let's just not use it!

Signed-off-by: Rémy Coutable <remy@rymai.me>

I noticed that the contributing guidelines still link to the thoughtbot
code review guidelines even though we already have our own.

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Add SCSS Lint, CSSComb config file, run SCSS Lint in GitLab CI, add documentation for SCSS Style Guide.

See !3069 for more information.

Also, link to this new paragraph in PROCESS.md and improved a bit this
document.

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Fixes #12784

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* Use 80 chars width where possible
* Remove easyfix label reference
* Add new issue submission template
* Add long links to the bottom of the page