Do not add leading/trailing ellipses when the string is less than excerpt lenght

Problem/Motivation

Highlighter processor always wraps the generated excerpt between ellipses, even if the original string's length than the configured excerpt max length.

Steps to reproduce

Excerpt length: 256

Original value: Routes a private network through a Cloudflare Tunnel.
Generated excerpt: … Routes a private network through a Cloudflare Tunnel. …

Proposed resolution

Only wrap the string when it was truncated and/or extracted from the context of a longer string.

Remaining tasks