fix(GlDrawer): change drawer horizontal padding

What does this MR do?

This MR resolves #2089 (closed)

According to Pajamas UI Kit in Figma, horizontal padding should be 16px horizontal.

All current drawers have bigger padding that calculates to 24px

Goal of this MR is to change drawer padding from 24px -> 16px.

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines.
• GitLab UI's contributing guidlines.
• If it changes a Pajamas-compliant component's look & feel, the MR has been reviewed by a UX designer.
• If it changes GitLab UI's documentation guidelines, the MR has been reviewed by a Technical Writer.
• If the MR changes a component's API, integration MR(s) have been opened in the following projects to ensure that the @gitlab/ui package can be upgraded quickly after the changes are released:
  • GitLab: mr_url
  • CustomersDot: mr_url
  • Status Page: mr_url
• Added the ~"component:*" label(s) if applicable.

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• Security reports checked/validated by a reviewer from the AppSec team

Accessibility

If this MR adds or modifies a component, take a few moments to review the following:

• All actions and functionality can be done with a keyboard.
• Links, buttons, and controls have a visible focus state.
• All content is presented in text or with a text equivalent. For example, alt text for SVG, or aria-label for icons that have meaning or perform actions.
• Changes in a component’s state are announced by a screen reader. For example, changing aria-expanded="false" to aria-expanded="true" when an accordion is expanded.
• Color combinations have sufficient contrast.

Screenshots

Before	After
--

Affected drawers

Here is a list of components in gitlab using drawer

GlDrawer uses in GitLab

• ~/pipeline_editor/components/drawer/pipeline_editor_drawer.vue
• ~/crm/components/form.vue
• ~/whats_new/components/app.vue
• ~/boards/components/board_content_sidebar.vue
• ~/boards/components/board_settings_sidebar.vue
• ee/roadmap/components/roadmap_settings.vue
• ee/security_orchestration/components/policy_drawer/policy_drawer.vue
• ee/requirements/components/requirement_form.vue
• ee/boards/components/epic_board_content_sidebar.vue
• ee/security_configuration/dast_profiles/dast_profiles_sidebar/dast_profiles_sidebar.vue
  • This is the only one currently opting in to a stick header.
• ee/compliance_dashboard/components/drawer.vue

Drawer	Screenshot after padding change
~/pipeline_editor/components/drawer/pipeline_editor_drawer.vue
~/crm/components/form.vue
~/whats_new/components/app.vue
~/boards/components/board_content_sidebar.vue
~/boards/components/board_settings_sidebar.vue
ee/roadmap/components/roadmap_settings.vue
ee/security_orchestration/components/policy_drawer/policy_drawer.vue
ee/requirements/components/requirement_form.vue
ee/boards/components/epic_board_content_sidebar.vue
ee/compliance_dashboard/components/drawer.vue

Closes #2089 (closed)