Improve HTML filtering performance

[AdamWr]

Similar issue like in - #1772

Steps to reproduce

1. Add this rule to the user rules: @@||nhk.or.jp^$content,badfilter
2. Open view-source:https://www3.nhk.or.jp/nhkworld/en/news/tags/2/
3. Measure the loading time (in my case it's about 8-10 seconds)
4. Now disable/remove this rule: @@||nhk.or.jp^$content,badfilter
5. Refresh the page a few times and measure the loading time
6. In my case it's about 1.5 - 2.5 seconds

Screenshot

Screenshot with $content exception

---

Note

AdGuard for Windows 7.16.0 nightly 20 (4551) (CL 1.13.115, DL 2.4.38)