fix: "cannot access variable before initialization" errors in route2

[sainthkh]

• Closes cy.route2 errors leak between tests #8926

User facing changelog

Cannot access 'continueSent' before initialization error happened intermittently. This PR fixes this issue.

Additional details

• Why was this change necessary? => Fix flaky failures.
• What is affected by this change? => N/A
• Any implementation details to explain? => It was happening because let variables should be used after its declaration unlike var variables. I fixed this by reordering declarations.

How has the user experience changed?

N/A

PR Tasks

• Have tests been added/updated? => Adding tests is a bit tricky. We can copy and paste the test in this comment, but it might not alarm even if there is an error because it's a flaky failure.
• 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?

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[flotwig]

LGTM. Thank you @sainthkh :)

[flotwig]

Regarding adding tests... I wonder if a linter rule could catch this

[flotwig]

Bleh, I tried adding the no-use-before-define rule but it turns out we have about 1,000,000 no-use-before-define violations in our codebase, so...