Respect the `sessionCookie` flag for the SC_GU_LA cookie [#MEM-403]

This is part of the work to enforce that users are recently signed-in
when they view their personal profile:

https://profile.theguardian.com/account/edit

The Identity API will now be proving Cookie info for the new SC_GU_LA
cookie, which stores when the user last authenticated:

https://github.com/guardian/identity/pull/176

...this change to NGW Frontend is required to get it to respect the new
`sessionCookie` flag, so that the SC_GU_LA cookie is only session-scoped
and dies when the user closes the browser.

https://jira.gutools.co.uk/browse/MEM-403
fixing tag breakout rules
fixing popular vid spacing
Fronts on-page description
removing legacy classes
renaming css class
Remove unused list
Sublink hover behaviour
remove placeholder of on-page description field
Merge pull request #6209 from guardian/unused-football-list

Remove unused list
removing old article class
Merge pull request #6210 from guardian/content-css-refactoring

Content css refactoring
Merge pull request #6202 from guardian/popular-vid-fix

fixing popular vid spacing
Merge pull request #6201 from guardian/tagfix

fixing tag breakout rules
remove "twitter:image:src" meta tag
Merge pull request #6193 from guardian/support-session-scoped-identity-cookies

Respect the `sessionCookie` flag for the SC_GU_LA cookie [#MEM-403]
Fix flakey Slice with Cards test
Merge pull request #6213 from guardian/fix-flakey-test

Fix flakey Slice with Cards test
Revert "Respect the `sessionCookie` flag for the SC_GU_LA cookie [#MEM-403]"
Merge pull request #6214 from guardian/revert-6193-support-session-scoped-identity-cookies

Revert "Respect the `sessionCookie` flag for the SC_GU_LA cookie [#MEM-4...