Update GlDrawer header-height usage of nav-sidebar to element which exists when super sidebar is enabled

From: !114676 (comment 1352187015)

GlDrawer usage header-height referencing .nav-sidebar an element to determine offsetHeight, this element no longer exists with the super sidebar and should be updated to .content-wrapper (to be consistent with other usage) or update all usage to .layout-page so that the padding-top provided from $calc-application-header-height is obvious.

Usage includes but is not limited to:

• https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/app/assets/javascripts/security_configuration/dast_profiles/constants.js#L4
• https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/app/assets/javascripts/security_configuration/dast_pre_scan_verification/components/pre_scan_verification_sidebar.vue#L46

Note: some components have containerClass prop defined, so the usage of the component will need to also be verified to be using a DOM element that exists for both super-sidebar (new nav) and contextual-sidebar (old nav)