chore: Fix rerunning multidomain tests

[chrisbreiding]

• Closes Multidomain: Can't rerun tests #18043

User facing changelog

N/A - Multidomain WIP

Additional details

Issue was caused by the secondary domain bridge iframe not existing and not being re-created on rerun.

Previously kept state in the driver for which domains were visited and had their bridge iframes already loaded (so they're not needlessly re-created between tests), but the iframes get cleared out between test runs, so it's better to let the runner, which controls the iframes, essentially keep that state instead.

PR Tasks

• Have tests been added/updated?
• N/A Has the original issue or this PR been tagged with a release in ZenHub?
• N/A Has a PR for user-facing changes been opened in cypress-documentation?
• N/A Have API changes been updated in the type definitions?
• N/A Have new configuration options been added to the cypress.schema.json?

[cypress-bot]

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[cypress]

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Test summary

8610 • 2 • 104 • 4 • 6

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Run details

Project	cypress
Status	Failed
Commit	a5e0ace
Started	Sep 14, 2021 3:01 PM
Ended	Sep 14, 2021 3:12 PM
Duration	10:59 💡
OS	Linux Debian - 10.9
Browser	Multiple

View run in Cypress Dashboard ➡️

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Failures

	commands/actions/type_spec.js		1
1	... > element
	e2e/focus_blur_spec.js		1
1	intercept blur methods correctly > focus area

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Flakiness

	commands/net_stubbing_spec.ts		2
1	network stubbing > waiting and aliasing > can timeout waiting on a single request using "alias.request"
2	network stubbing > intercepting request > can intercept utf-8 request bodies without crashing
	commands/xhr_spec.js		1
1	src/cy/commands/xhr > abort > aborts xhrs currently in flight
	dom/visibility_spec.ts		1
1	... > has `opacity: 0`
	cypress/proxy-logging-spec.ts		1
1	Proxy Logging > request logging > fetch log shows resource type, url, method, and status code and has expected snapshots and consoleProps
This comment includes only the first 5 flaky tests. See all 6 flaky tests in the Cypress Dashboard.

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[jennifer-shehane]

Verified that this test hangs when it does not include the code from this PR. Manually works on rerunning multidomain tests.