tests: fix CI. execContext count, i18n ICU breakage, loud jsdom parse output

[paulirish]

fixing up CI. breakages and messy test logs.

• Fix api-test-pptr.js failure: Recent Chromium (ToT) started spawning many more isolated execution contexts (utility worlds, etc.), which broke the "exactly 2" unique ID assertion. We now filter for only "default" contexts.
• Fix i18n-formatter-test.js failure: Node 24+ changed duration formatting (e.g. German "1 Std." -> "1h Std."). Expectations are now more relaxed to accommodate environmental differences in Intl output.
• Silence JSDOM noise: Silenced the massive Error: Could not parse CSS stylesheet logs by using a VirtualConsole. These were non-fatal errors caused by jsdom 12 being unable to parse modern CSS (like @container and cqi units).