Use regular compiler seeing as ECJ doesn't support Java 21 JRE

By: md_5 <git@md-5.net>

paper-server/pom.xml

@@ -477,18 +477,9 @@
                 <artifactId>maven-compiler-plugin</artifactId>
                 <version>3.13.0</version>
                 <configuration>
-                    <!-- we use the Eclipse compiler as it doesn't need a JDK -->
-                    <compilerId>eclipse</compilerId>
                     <!-- default changed with version 3.11.0 -->
                     <showWarnings>false</showWarnings>
                 </configuration>
-                <dependencies>
-                    <dependency>
-                        <groupId>org.codehaus.plexus</groupId>
-                        <artifactId>plexus-compiler-eclipse</artifactId>
-                        <version>2.15.0</version>
-                    </dependency>
-                </dependencies>
             </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>