Fix BECS and BLIK e2e test configuration

[daledupreez]

Changes proposed in this Pull Request:

This PR ensures that the run-e2e-tests workflow uses the correct internal variable when selecting the Stripe keys to use for BECS and BLIK e2e tests. Prior to this fix, we would incorrectly use the standard keys and would then see failures in the tests due to the payment methods not being available.

Testing instructions

Testing for this will be via GitHub itself.

• Navigate to https://github.com/woocommerce/woocommerce-gateway-stripe/actions/workflows/manual-e2e-tests.yml
• Click on the "Run workflow" button
• Ensure that you pick fix/secret-resolution-for-lpm-e2e-tests from the "Use workflow from" dropdown
• Feel free to leave all other fields as their default values (or pick a value like release/10.0.1 for the "Branch, Tag or SHA to checkout" field)
• Click on the "Run workflow" button
• Verify that the becs and blik e2e tests for the workflow complete successfully

You could also take a look at https://github.com/woocommerce/woocommerce-gateway-stripe/actions/runs/18555110727, which is a run I kicked off from this branch -- you can see that the blik and becs e2e tests pass, where they failed in the previous runs.

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• Covered with tests (or have a good reason not to test in description ☝️)
• Tested on mobile (or does not apply)

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Comment

This PR modifies a GitHub workflow and has no user-facing impact.

Post merge

• Added testing instructions to the Release Testing Instructions wiki page (or does not apply)
• Added the needs docs label (or does not apply)
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[wjrosa]

Nice! Change looks good to me

[malithsen]

Thanks for fixing this. Looks good!