Switch to global attributes and remove section-scoped pull and issue

[joepeeples]

Changes all instances of book/section-scoped attributes {pull} and {issue} to global attributes {kibana-pull} and {kibana-issue}, within the main branch.

Also removes the book/section-scoped definitions from the index file release-notes.asciidoc.

Note

We also made this change to the 7.17 branch with #4978. We didn't update any other currently available branches because they're unlikely to be part of the migration. When we migrate, we'll only be migrating main, 7.17, and whatever the current branch is at that time (probably 8.15 by that point, definitely not 8.13).

[github-actions]

A documentation preview will be available soon.

• 🔨 Buildkite builds
• 📚 HTML diff
• 📙 Preview page

Request a new doc build by commenting

• Rebuild this PR: run docs-build
• Rebuild this PR and all Elastic docs: run docs-build rebuild

_{run docs-build is much faster than run docs-build rebuild. A rebuild should only be needed in rare situations.}

_{If your PR continues to fail for an unknown reason, the doc build pipeline may be broken. Elastic employees can check the pipeline status here.}

[mergify]

This pull request does not have a backport label. Could you fix it @joepeeples? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• v7.x is the label to automatically backport to the 7.x branch.
• v7./d./d is the label to automatically backport to the 7./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.

[jmikell821]

Reviewed this twice; LGTM :)