fix: show correct error message when a regex starting with = is passed to cy.contains.

[sainthkh]

• Closes Unrecognized expression for regex that ends with /=\s+[0-6]/  #21108

User facing changelog

Correct error message is shown and Cypress is properly retried when a regex starting with = is passed to cy.contains.

Additional details

• Why was this change necessary? => Cypress doesn't work correctly when a regex starting with = is passed to cy.contains.
• What is affected by this change? => N/A
• Any implementation details to explain? => It was happening because Sizzle, jQuery selector engine escapes = to handle attribute selectors. I changed our jquery config code to handle this exceptional case.

How has the user experience changed?

// Before: Fail with Syntax Error message + doesn't retry.
// After: Timed out error message + retry.
cy.contains(/=[0-6]/) 

PR Tasks

• Have tests been added/updated?
• Has the original issue (or this PR, if no issue exists) been tagged with a release in ZenHub? (user-facing changes only)
• [na] Has a PR for user-facing changes been opened in cypress-documentation?
• [na] Have API changes been updated in the type definitions?
• [na] Have new configuration options been added to the cypress.schema.json?

[cypress-bot]

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[BlueWinds]

For anyone looking at this later, note that the selector already finds the element if it exists on the page - this PR just ensures that Cy waits for it to exist if it doesn't already. See #21108 (comment).

[cypress-bot]

Released in 9.7.0.

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