Add `Delete` button to label edit view

What does this MR do and why?

Related to #345195 (closed)

Adds a Delete button to the label edit view. This change affects Project, Group, and Admin label management.

Screenshots or screen recordings

Admin labels

Desktop

Before	After

Mobile

Before	After

Project labels

Desktop

Before	After

Mobile

Before	After

Group labels

Desktop

Before	After

Mobile

Before	After

How to set up and validate locally

Admin labels

1. Navigate to /admin/labels
2. Create a label
3. Edit the label

Project labels

1. Navigate to a project -> Project information -> Labels
2. Create a label
3. Edit the label

Group labels

1. Navigate to a group -> Group information -> Labels
2. Create a label
3. Edit the label

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

.gitlab/issue_templates/Experiment Rollout.md

-<!-- Title suggestion: [Experiment Rollout] experiment-key - description of experiment -->
+<!-- Title suggestion: [Experiment Rollout] feature-flag-name - description of experiment -->
 
 ## Summary
 
 This issue tracks the rollout and status of an experiment through to removal.
 
-1. Experiment key / feature flag name: `<experiment-key>`
+1. Feature flag name: `<feature-flag-name>`
 1. Epic or issue link: `<issue or epic link>`
 
 This is an experiment rollout issue
@@ -55,7 +55,7 @@ Note: you can use the [CXL calculator](https://cxl.com/ab-test-calculator/) to d
 - Runtime in days, or until we expect to reach statistical significance: `30`
 - We will roll this out behind a feature flag and expose this to `<rollout-percentage>`% of actors to start then ramp it up from there.
 
-`/chatops run feature set <experiment-key> <rollout-percentage> --actors`
+`/chatops run feature set <feature-flag-name> <rollout-percentage> --actors`
 
 ### Status
 
@@ -83,14 +83,14 @@ In this rollout issue, ensure the scoped `experiment::` label is kept accurate.
 ## Roll Out Steps
 
 - [ ] [Confirm that end-to-end tests pass with the feature flag enabled](https://docs.gitlab.com/ee/development/testing_guide/end_to_end/feature_flags.html#confirming-that-end-to-end-tests-pass-with-a-feature-flag-enabled). If there are failing tests, contact the relevant [stable counterpart in the Quality department](https://about.gitlab.com/handbook/engineering/quality/#individual-contributors) to collaborate in updating the tests or confirming that the failing tests are not caused by the changes behind the enabled feature flag.
-- [ ] Enable on staging (`/chatops run feature set <experiment-key> true --staging`)
+- [ ] Enable on staging (`/chatops run feature set <feature-flag-name> true --staging`)
 - [ ] Test on staging
 - [ ] Ensure that documentation has been updated
-- [ ] Enable on GitLab.com for individual groups/projects listed above and verify behaviour  (`/chatops run feature set --project=gitlab-org/gitlab feature_name true`)
+- [ ] Enable on GitLab.com for individual groups/projects listed above and verify behaviour  (`/chatops run feature set --project=gitlab-org/gitlab <feature-flag-name> true`)
 - [ ] Coordinate a time to enable the flag with the SRE oncall and release managers
   - In `#production` mention `@sre-oncall` and `@release-managers`. Once an SRE on call and Release Manager on call confirm, you can proceed with the rollout
 - [ ] Announce on the issue an estimated time this will be enabled on GitLab.com
-- [ ] Enable on GitLab.com by running chatops command in `#production` (`/chatops run feature set feature_name true`)
+- [ ] Enable on GitLab.com by running chatops command in `#production` (`/chatops run feature set <feature-flag-name> true`)
 - [ ] Cross post chatops Slack command to `#support_gitlab-com` ([more guidance when this is necessary in the dev docs](https://docs.gitlab.com/ee/development/feature_flags/controls.html#where-to-run-commands)) and in your team channel
 - [ ] Announce on the issue that the flag has been enabled
 - [ ] Remove experiment code and feature flag and add changelog entry - a separate [cleanup issue](https://gitlab.com/gitlab-org/gitlab/-/issues/new?issuable_template=Experiment%20Successful%20Cleanup) might be required
@@ -102,7 +102,7 @@ In this rollout issue, ensure the scoped `experiment::` label is kept accurate.
 - [ ] This feature can be disabled by running the following Chatops command:
 
 ```
-/chatops run feature set <experiment-key> false
+/chatops run feature set <feature-flag-name> false
 ```
 
 ## Experiment Successful Cleanup Concerns