Remove leftover libsystemd references (#112078)

Systemd notification now happens by directly communicating with the
systemd socket. This commit removes the native access to libsystemd,
which is no longer used.

Author: rjernst

libs/native/jna/src/main/java/org/elasticsearch/nativeaccess/jna/JnaNativeLibraryProvider.java

@@ -15,7 +15,6 @@
 import org.elasticsearch.nativeaccess.lib.NativeLibrary;
 import org.elasticsearch.nativeaccess.lib.NativeLibraryProvider;
 import org.elasticsearch.nativeaccess.lib.PosixCLibrary;
-import org.elasticsearch.nativeaccess.lib.SystemdLibrary;
 import org.elasticsearch.nativeaccess.lib.VectorLibrary;
 import org.elasticsearch.nativeaccess.lib.ZstdLibrary;
 
@@ -38,8 +37,6 @@ public JnaNativeLibraryProvider() {
                 JnaMacCLibrary::new,
                 Kernel32Library.class,
                 JnaKernel32Library::new,
-                SystemdLibrary.class,
-                JnaSystemdLibrary::new,
                 ZstdLibrary.class,
                 JnaZstdLibrary::new,
                 VectorLibrary.class,

libs/native/jna/src/main/java/org/elasticsearch/nativeaccess/jna/JnaSystemdLibrary.java

@@ -9,5 +9,5 @@
 package org.elasticsearch.nativeaccess.lib;
 
 /** A marker interface for libraries that can be loaded by {@link org.elasticsearch.nativeaccess.lib.NativeLibraryProvider} */
-public sealed interface NativeLibrary permits JavaLibrary, PosixCLibrary, LinuxCLibrary, MacCLibrary, Kernel32Library, SystemdLibrary,
-    VectorLibrary, ZstdLibrary {}
+public sealed interface NativeLibrary permits JavaLibrary, PosixCLibrary, LinuxCLibrary, MacCLibrary, Kernel32Library, VectorLibrary,
+    ZstdLibrary {}

libs/native/src/main/java/org/elasticsearch/nativeaccess/lib/NativeLibrary.java

@@ -14,7 +14,6 @@
 import org.elasticsearch.nativeaccess.lib.MacCLibrary;
 import org.elasticsearch.nativeaccess.lib.NativeLibraryProvider;
 import org.elasticsearch.nativeaccess.lib.PosixCLibrary;
-import org.elasticsearch.nativeaccess.lib.SystemdLibrary;
 import org.elasticsearch.nativeaccess.lib.VectorLibrary;
 import org.elasticsearch.nativeaccess.lib.ZstdLibrary;
 
@@ -36,8 +35,6 @@ public JdkNativeLibraryProvider() {
                 JdkMacCLibrary::new,
                 Kernel32Library.class,
                 JdkKernel32Library::new,
-                SystemdLibrary.class,
-                JdkSystemdLibrary::new,
                 ZstdLibrary.class,
                 JdkZstdLibrary::new,
                 VectorLibrary.class,