Migrate gl-dropdown to gl-disclosure-dropdown

What does this MR do and why?

This MR implements #424768 (closed) and changes GlDisclosureDropdown component to GlDisclosureDropdown.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Create a project with deployment configuration that would result in having environments within a folder

Example configuration

stages:
    - deploy
    - stop
image: alpine:latest

deploy:to-folder:
  stage: deploy
  script: echo "done"
  environment: folder/env-1

deploy:to-folder-2:
  stage: deploy
  script: echo "done"
  environment: folder/env-2

2. Navigate to Operate -> Environments, expand the environments folder and click "show all"
3. Check that the elispis button behaves properly and shows the actions.

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.