Adding type::ignore label to exclude Issues from type nudges

What does this MR do and why?

Based on suggestions, feedback, and to respect our communication guidelines regarding issues, the Next-prioritization working group proposed creating a new type::ignore label. Applying this label to an Issue in the gitlab-org namespace will cause it to be skipped by the type-labeling nudge from the GitLab bot. This MR implements the skipping behavior. It also adds clarifying text to let users know about this new option.

Expected impact & dry-runs

These are strongly recommended to assist reviewers and reduce the time to merge your change.

Dry-run test results:

• I have created this test issue before triggering the following dry-runs against the gitlab project:

1. Leave the test issue without any label:
   • https://gitlab.com/gitlab-org/quality/triage-ops/-/jobs/2840885443
   • gitlab-org/gitlab#370406 is one of the targeted resources (searching 370406 in the stacktrace returns the following:)

# https://gitlab.com/gitlab-org/gitlab/-/issues/370406

:wave: @jennli, please add a [type label](https://docs.gitlab.com/ee/development/contributing/issue_workflow.html#type-labels) and a [subtype label](https://about.gitlab.com/handbook/engineering/metrics/#work-type-classification) to this issue
to help with better milestone planning and [issue discovery in issue reports](https://about.gitlab.com/handbook/engineering/quality/triage-operations/#group-level-bugs-features-and-ux-debt).
If you do not feel the purpose of this issue matches one of the types, you may apply the `type::ignore` label to exclude it from type tracking metrics and future prompts.
---
([improve this comment?](https://gitlab.com/gitlab-org/quality/triage-ops/-/blob/master/policies/stages/hygiene/prompt-team-member-type-label.yml))
/label ~"auto updated"

2. Update the test issue by labeling it with typeignore:
   • https://gitlab.com/gitlab-org/quality/triage-ops/-/jobs/2840896488
   • gitlab-org/gitlab#370406 is not a targeted resource (searching 370406 in the stacktrace doesn't return anything )

See https://gitlab.com/gitlab-org/quality/triage-ops/-/tree/master/doc/scheduled#testing-with-a-dry-run on how to perform dry-runs.

Action items

• (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable) Identify the affected groups and how to communicate to them:
  • /cc @person_or_group =>
  • Relevant Slack channels =>
  • Engineering week-in-review