use same pin-set for download server (#898)

Corona-Warn-App/src/main/res/xml/network_security_config.xml

@@ -3,6 +3,7 @@
 
     <domain-config cleartextTrafficPermitted="false">
         <domain includeSubdomains="true">coronawarn.app</domain>
+        <domain includeSubdomains="true">main.px.t-online.de</domain>
         <pin-set
             expiration="2024-02-12"
             tools:ignore="MissingBackupPin">
@@ -15,13 +16,4 @@
         </trust-anchors>
     </domain-config>
 
-    <domain-config cleartextTrafficPermitted="false">
-        <domain includeSubdomains="true">main.px.t-online.de</domain>
-        <trust-anchors>
-            <certificates
-                overridePins="false"
-                src="system" />
-        </trust-anchors>
-    </domain-config>
-
 </network-security-config>
\ No newline at end of file