DUPP-218 Always hide welcome notice to upgrading users

[enricobattocchi]

Context

• We want to hide the welcome notice to upgrading users, even if they have not dismissed the upgrade notice yet.

Summary

This PR can be summarized in the following changelog entry:

• Fixes an unreleased bug where the welcome notice would be displayed to existing users who haven't dismissed the upgrade notice.

Relevant technical choices:

• I failed to change the commit message so it's not meaningful. Sorry.

Test instructions

Test instructions for the acceptance test before the PR gets merged

This PR can be acceptance tested by following these steps:

Preparation

• install Local By Flywheel
• create two websites: one for a New User, another for an Existing User
• checkout this branch and create a ZIP with grunt artifact.

New user

• in the website for the New User, install the artifact.zip file you created
• activate the plugin
• check that you can see the Welcome notice in the Dashboard and in the Plugins page.

Existing user

• in the website for the Existing User, install the latest Yoast Duplicate Post version from WP.org
• activate the plugin
• you'll see the upgrade notice in the Dashboard and in the Plugins page. Do not dismiss it
• install the artifact.zip file you created to overwrite the existing version
• check that you cannot see the Welcome notice in the Dashboard and in the Plugins page.

Test instructions for QA when the code is in the RC

• [x] QA should use the same steps as above.

QA can test this PR by following these steps:

*

Impact check

This PR affects the following parts of the plugin, which may require extra testing:

*

UI changes

• [ ] This PR changes the UI in the plugin. I have added the 'UI change' label to this PR.

Documentation

• [ ] I have written documentation for this change.

Quality assurance

• [x] I have tested this code to the best of my abilities
• [ ] I have added unittests to verify the code works as intended

Fixes DUPP-218

[pls78]

CR ✅ && ACC ✅