Restore breadcrumb border for all pages

What does this MR do and why?

From: https://gitlab.slack.com/archives/C010NAWPRV4/p1679266947944489

Restore breadcrumb border removed in !113390 (merged) to enable border and spacing to be consistent when super sidebar collapse update is implemented.

Changes

• Restore border styles on .breadcrumb-container
• Remove @no_breacrumb_border variable usage from templates
• Remove @no_breacrumb_border removing border styles
• Update top spacing in templates to $gl-spacing-scale-4 (12px)
• Update .page-title spacing to $gl-spacing-scale-4 (12px) when inside .page-title-holder
• Update "New issue" page to use .page-title-holder

Screenshots or screen recordings

Page	Before	After
Epic
Issue
New issue
Projects
Project
Milestone
Issues
Merge requests
To-do list
Incident
Files

How to set up and validate locally

• Epic http://127.0.0.1:3000/groups/flightjs/-/epics/5
• Issue http://127.0.0.1:3000/flightjs/Flight/-/issues/33
• New issue http://127.0.0.1:3000/flightjs/Flight/-/issues/new
• Projects http://127.0.0.1:3000/dashboard/projects
• Project http://127.0.0.1:3000/flightjs/Flight
• Milestone http://127.0.0.1:3000/flightjs/Flight/-/milestones/6#tab-issues
• Issues http://127.0.0.1:3000/dashboard/issues?sort=priority&state=opened&assignee_username[]=root
• Merge requests http://127.0.0.1:3000/dashboard/merge_requests?assignee_username=root
• To-do list http://127.0.0.1:3000/dashboard/todos
• Incident http://127.0.0.1:3000/flightjs/Flight/-/issues/incident/34
• Files http://127.0.0.1:3000/flightjs/Flight/-/tree/master

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.