[5.3] Do not display modified url in update check

[laoneo]

Summary of Changes

Follow up for #44516. The modified url should not be displayed after the update site is fetched as it can contain sensitive data. Better to assign the url to a new variable.

Testing Instructions

Add the following code to the file /plugins/installer/packageinstaller/src/Extension/PackageInstaller.php

public function onInstallerBeforeUpdateSiteDownload(\Joomla\CMS\Event\Installer\BeforeUpdateSiteDownloadEvent $event): void
{
        $event->updateUrl($event->getUrl().'demo=1');
}

and replace the line 47 with:

return ['onInstallerAddInstallationTab' => 'onInstallerAddInstallationTab', 'onInstallerBeforeUpdateSiteDownload' => 'onInstallerBeforeUpdateSiteDownload'];

• Go to /administrator/index.php?option=com_installer&view=update
• Click on "Check for updates"

Actual result BEFORE applying this Pull Request

The parameter demo=1 is shown in the warning message.

Expected result AFTER applying this Pull Request

The parameter demo=1 is not shown in the warning message.

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[dgrammatiko]

I have tested this item ✅ successfully on 1197dd1

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[alikon]

I have tested this item ✅ successfully on 1197dd1

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/45373.}

[alikon]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/45373.}

[rdeutz]

Thanks