[cleanupIDs] symbol is incorrectly removed when its ID is only used by URL-encoded reference

[ctrlcctrlv]

Describe the bug
symbol is incorrectly removed when its ID is only used by URL-encoded reference.

Example files: https://gist.github.com/ctrlcctrlv/a985bd9fdf31ecc7e414ab29d49576ae

To Reproduce
Steps to reproduce the behavior:

svgo --config svgo.config.js -i working.svg -o working_o.svg
svgo --config svgo.config.js -i broken.svg -o broken_o.svg

Observe missing elements:

Expected behavior
No elements to be missing:

Desktop (please complete the following information):

• SVGO Version 2.7.0
• NodeJs Version v12.22.9
• OS: Pop! OS 22.04

Code issue

You cannot just do a basic string comparison on hyperlink references. This will never work how its implementor intended.

Direct git blame is to:

svgo/plugins/cleanupIDs.js

Line 16 in a9834ef

const regReferencesHref = /^#(.+?)$/;

By @TrySound.

However this bug dates back to original implementation of the plugin, making it ten years old. 40ab776 by @deepsweet.