Issue/11114 avoid tracking signup as error

[JorgeMucientes]

Closes: #11114

Description

Small change on how we track failures during login step in Jetpack installation flow. Full discussion here: p1732113936622179/1731431785.549369-slack-C03L1NF1EA3 TLDR: We won't track signup case as woocommerceandroid_jetpack_setup_login_flow, Properties: {"step":"email_address","failure":"UNKNOWN_USER", ... event anymore.

Additionally this PR adds a small update on username_not_registered_wpcom removing the Hmm part and just leaving it as: We can\'t find a WordPress.com account connected to this username. You can enter an email to create a new account.

Testing information

1. Log into a self hosted site that is not Jetpack connected
2. Click on Jetpack banner and enter an invalid username
3. Check that the error message is shown as expected and check that woocommerceandroid_jetpack_setup_login_flow, Properties: {"step":"email_address","failure":"UNKNOWN_USER" is tracked in the Logcat
4. Erase the invalid username and enter a unknown WP.com email
5. Check that no event for failure is tracked.

The tests that have been performed

The above

Images/gif

• [x] I have considered if this change warrants release notes and have added them to RELEASE-NOTES.txt if necessary. Use the "[Internal]" label for non-user-facing changes.

Reviewer (or Author, in the case of optional code reviews):

Please make sure these conditions are met before approving the PR, or request changes if the PR needs improvement:

• [ ] The PR is small and has a clear, single focus, or a valid explanation is provided in the description. If needed, please request to split it into smaller PRs.
• [ ] Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• [ ] Manual Testing: The author listed all the tests they ran, including smoke tests when needed (e.g., for refactorings). The reviewer confirmed that the PR works as expected on big (tablet) and small (phone) in case of UI changes, and no regressions are added.

[dangermattic]

	1 Warning
:warning:	This PR is assigned to the milestone 21.2. This milestone is due in less than 2 days. Please make sure to get it merged by then or assign it to a milestone with a later deadline.

Generated by :no_entry_sign: Danger

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce-Wear Android by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce-Wear Android
	Platform	⌚️ Wear OS
	Flavor	Jalapeno
	Build Type	Debug
	Commit	248436e96b32038db37d58f6eeab0a56f6f1b3d9
	Direct Download	woocommerce-wear-prototype-build-pr12973-248436e.apk

[wpmobilebot]

📲 You can test the changes from this Pull Request in WooCommerce Android by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce Android
	Platform	📱 Mobile
	Flavor	Jalapeno
	Build Type	Debug
	Commit	248436e96b32038db37d58f6eeab0a56f6f1b3d9
	Direct Download	woocommerce-prototype-build-pr12973-248436e.apk

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 39.73%. Comparing base (60fc8b4) to head (248436e). Report is 3 commits behind head on trunk.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## trunk #12973 +/- ## ========================================= Coverage 39.73% 39.73% Complexity 5985 5985 ========================================= Files 1268 1268 Lines 73252 73252 Branches 10061 10061 ========================================= Hits 29106 29106 Misses 41564 41564 Partials 2582 2582 ```

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