Streamline onboarding: Update E2E tests for the conditionally hidden WordPress.com account connection setting

[joemcgill]

Changes proposed in this Pull Request:

See #2487. This is meant to be added to the existing PR prior to final code review/merging. Opening this as a separate PR to ease internal review.

This updates the e2e tests following the removal of the WP.com account.

First, this moves the test for confirming that the WP.com card is not shown after it's connected to a new test described by "Connected WordPress.com account", which mocks the Jetpack connection before loading the page.

Second, one the WP.com account card is no longer shown, many of the following e2e tests that relied on nth-locators to find elements in the DOM needed to be refactored so that they work regardless of whether the WP.com card was present.

To do so, this updates the getAccountCards() method to accept options that get passed to the locator locator (see docs) to find a specific account card, which can then be used in other helper methods when trying to locate a specific title or description.

Detailed test instructions:

1. If using wp-env locally, run npm run test:e2e -- setup-mc

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.5%. Comparing base (e2f2420) to head (7523a05).
Report is 3 commits behind head on update/2487-hide-jetpack-if-already-connected-onboarding.

Additional details and impacted files

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##           update/2487-hide-jetpack-if-already-connected-onboarding   #2521     +/-   ##
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- Coverage                                                      63.7%   63.5%   -0.2%     
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  Lines                                                          5084    5043     -41     
  Branches                                                       1228    1220      -8     
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- Hits                                                           3240    3204     -36     
+ Misses                                                         1677    1672      -5     
  Partials                                                        167     167             

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js-unit-tests	63.5% <ø> (-0.2%)	⬇️

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