Update policy editor alert to be sticky

What does this MR do and why?

Describe in detail what your merge request does and why.

Create sticky alert for policy editor

• add sticky prop for GlAlert
• add CSS to set position below top bar

Changelog: changed

EE: true

Screenshots or screen recordings

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Scenario	Before	After
Single error
Multiple errors

How to set up and validate locally

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

1. Navigate to http://gdk.test:3443/flightjs/Flight/-/security/policies/new?type=scan_execution_policy yaml mode
2. Insert the following yaml

name: 'test'
description: ''
enabled: true
rules:
  - type: pipeline
    branches:
      - '*'
actions:
  - scan:
    site_profile: ''
    scanner_profile: ''
    tags: {}

3. Save the yaml and notice alert

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.

Related to #379118 (closed)