Based on the
https://gitlab.com/gitlab-org/gitlab-ee/issues/8429
issue for the required pipeline configuration setting.

This updates redirected links in integration, update, user
and workflow dirs. Should now link to final URLs to avoid
redirect hops

Previously, we used brackets to denote the tier badges,
but this made Kramdown, the docs site Markdown renderer,
show many warnings when building the site. This is now
fixed by using parentheses instead of square brackets.

This was caused by [PREMIUM] looking like a link to
Kramdown, which couldn't find a URL there.

See:
- https://gitlab.com/gitlab-com/gitlab-docs/merge_requests/484
- https://gitlab.com/gitlab-org/gitlab-ce/issues/63800

Also adds and one linting rule
and makes project conform to it.

Issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/61201#

Apply suggestion to continuous_integration.md

- Also makes other minor Markdown fixes that were near the main fixes.

Signed-off-by: NTakuya Noguchi <takninnovationresearch@gmail.com>