[BUGFIX] Show correct alt Text in SystemEmail

Use alt text "Logo" (instead of "TYPO3 Logo") in the SystemEmail
Fluid layout if a custom logo is used.

The layout SystemEmail is used by default when sending Fluid emails.
It is for example used when sending a test email via the "Environment"
module in the install tool or "Admin Tools" in the backend.

If an image is configured in the backend Extension Configuration
login.loginLogo, this image is used and the text is added as alt
text.

Previously, "TYPO3 Logo" was always used as alt text, which is awkward
if the alt text is displayed instead of the logo, which may happen for
several reasons

Resolves: #100081
Releases: main, 11.5
Change-Id: Ia7c1d7ab7a008fb6ed2f3851db5e1af171a4af9f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78023


Tested-by: Torben Hansen <derhansen@gmail.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Torbe...

typo3/sysext/core/Resources/Private/Layouts/SystemEmail.html

@@ -352,7 +352,7 @@
                                 <td valign="top" class="image" align="center" style="padding: 0px 36px; padding-bottom: 20px; color: #222222;text-align: center;">
                                     <f:if condition="{typo3.systemConfiguration.backend.loginLogo}">
                                         <f:then>
-                                            <img src="{typo3.systemConfiguration.backend.loginLogo -> core:normalizedUrl()}" alt="TYPO3 Logo" height="41" width="150" />
+                                            <img src="{typo3.systemConfiguration.backend.loginLogo -> core:normalizedUrl()}" alt="Logo" height="41" width="150" />
                                         </f:then>
                                         <f:else if="{typo3.systemConfiguration.backend.loginHighlightColor}">
                                             <img src="{normalizedParams.siteUrl}{f:uri.resource(path: 'EXT:core/Resources/Public/Images/typo3_black.svg')}" alt="TYPO3 Logo" height="41" width="150" />