Fix alignment for DAST profile buttons

What does this MR do?

Fixes #292689 (closed)

This MR tries to align the button to be responsive in DAST site profiles library. This behavior can be quickly looked at https://gitlab.com/gitlab-org/security-products/dast-testing/-/security/configuration/dast_profiles#site-profiles

Todo

• Get UX Review
• Add vertical space between buttons

Screenshots (strongly suggested)

1. Full-width (no change, expect a small margin around the buttons)

Before	After

2. Small Devices

Before	After

3. Small Devices when the validation status changes

Before	After

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry feature flag
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

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
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team