Twig spaceless filter is deprecated

Problem/Motivation

The Twig spaceless filter is deprecated since twig 3.12.

The filter is used at:

• /templates/classy/field/link-formatter-link-separate.html.twig: Line 15
• /templates/classy/navigation/toolbar.html.twig: Line 30

Proposed resolution

While there is not a full replacement, use the whitespace control features from twig.

See https://twig.symfony.com/doc/3.x/filters/spaceless.html