Fix flaky system-tests-firefox job

[flotwig]

system-tests-firefox seems to fail frequently on snapshot matches when it takes longer than normal to launch Firefox:

https://app.circleci.com/pipelines/github/cypress-io/cypress/25418/workflows/c6f39a26-4ae6-4c34-a562-730b7d5e9001/jobs/953049

Two ways to fix it:

1. Support some env var like CYPRESS_CDP_CONNECTION_TIMEOUT in protocol.ts and pass it in system-tests.ts
2. Filter out the noisy stdout in system-tests.ts like we do for video snapshot errors in FF:

   cypress/system-tests/lib/system-tests.ts

   Lines 954 to 968 in 65458d6

   	try {
   	if (options.originalTitle) {
   	systemTests.snapshot(options.originalTitle, str, { allowSharedSnapshot: true })
   	} else {
   	systemTests.snapshot(str)
   	}
   	} catch (err) {
   	// firefox has issues with recording video. for now, ignore snapshot diffs that only differ in this error.
   	// @see https://github.com/cypress-io/cypress/pull/16731
   	if (!(options.browser === 'firefox' && isVideoSnapshotError(err))) {
   	throw err
   	}
   	console.log('(system tests warning) Firefox failed to process the video, but this is being ignored due to known issues with video processing in Firefox.')
   	}

[cypress-bot]

Released in 9.1.0.

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Cypress v9.1.0, please open a new issue.