Fix Unique visitors and Users metric shown in Users report

[tsteur]

Description:

Fix #19850

Removes Users and Unique Visitors metrics from the Users report. Those metrics don't make sense considering they would be always "1" except for the others row.

I also thought about additionally removing it from the API response (see diff below) but wasn't sure if we consider this a breaking API change. Figured in the API response the output of those metrics doesn't hurt as much and we can keep it there. In the UI the unneeded metrics "hurt" more considering it's processed by humans and it causes distraction.

diff --git a/plugins/UserId/API.php b/plugins/UserId/API.php
index a213466346..13256f5666 100644
--- a/plugins/UserId/API.php
+++ b/plugins/UserId/API.php
@@ -40,6 +40,9 @@ class API extends \Piwik\Plugin\API
         $dataTable->queueFilter('ReplaceColumnNames');
         $dataTable->queueFilter('ReplaceSummaryRowLabel');
         $dataTable->queueFilter('AddSegmentByLabel', array('userId'));
+        // Removing columns queued to improve performance. We could have 100K users in the table but only
+        // display 50 of them. We only want to perform this action on the 50 users.
+        $dataTable->queueFilter('ColumnDelete', array(array('nb_users', 'nb_uniq_visitors')));
 
         return $dataTable;
     }

Steps to reproduce

• Go:
  https://demo.matomo.cloud/index.php?module=CoreHome&action=index&idSite=1&period=day&date=yesterday#?period=day&date=2022-10-10&idSite=1&category=General_Visitors&subcategory=UserId_UserReportTitle
• Click on the Change Visualisation icon then Display a table with Visitor engagement metrics
• Then some unneeded metrics were displayed:
  
• With this patch they are no longer shown

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed

[michalkleiner]

Thanks for the PR, @tsteur. It seems we don't have this covered by tests as no test newly failed. @matomo-org/core-reviewers do we think we should add one?

[sgiehl]

I've added some simple UI tests