Move AspectJ Maven executions to default phases

Document the pros and cons in the POM with this comment:

Attention: aspectj-maven-plugin MUST be declared AFTER
maven-compiler-plugin, if they are both supposed to run in the same
default phases 'compile' and 'test-compile', but execution order is to
be guaranteed. Then, you have the convenience of being able to run e.g.
'mvn [clean] compile' instead of 'mvn [clean] process-classes'. For a
slightly less convenient, but less refactoring-error-prone solution,
see the commented-out phases below.

spring-data-jpa/pom.xml

@@ -357,6 +357,12 @@
 				</configuration>
 			</plugin>
 
+			<!--
+				Attention: aspectj-maven-plugin MUST be declared AFTER maven-compiler-plugin, if they are both supposed to run
+				in the same default phases 'compile' and 'test-compile', but execution order is to be guaranteed. Then, you have
+				the convenience of being able to run e.g. 'mvn [clean] compile' instead of 'mvn [clean] process-classes'. For a
+				slightly less convenient, but less refactoring-error-prone solution, see the commented-out phases below.
+			-->
 			<plugin>
 				<groupId>org.codehaus.mojo</groupId>
 				<artifactId>aspectj-maven-plugin</artifactId>
@@ -374,14 +380,14 @@
 						<goals>
 							<goal>compile</goal>
 						</goals>
-						<phase>process-classes</phase>
+						<!--<phase>process-classes</phase>-->
 					</execution>
 					<execution>
 						<id>aspectj-test-compile</id>
 						<goals>
 							<goal>test-compile</goal>
 						</goals>
-						<phase>process-test-classes</phase>
+						<!--<phase>process-test-classes</phase>-->
 					</execution>
 				</executions>
 				<configuration>