workaround html pipeline timeouts due to syntax highlighting
workaround html pipeline timeouts due to syntax highlighting

Closes #4276
Closes #4346

gjtorikian/html-pipeline,terracatta/html-pipeline,moskvax/html-pipeline,tricknotes/html-pipeline,kbrock/html-pipeline,gjtorikian/html-pipeline,jch/html-pipeline,kbrock/html-pipeline,jch/html-pipeline,github/html-pipeline,moskvax/html-pipeline,nono/html-pipeline-linuxfr,terracatta/html-pipeline,charliesome/html-pipeline,github/html-pipeline