Avoid javadoc:aggregate

[jglick]

After #3442 there was apparently another release failure. I suspect this fixes it.

[jglick]

Problem can be reproduced by running

mvn -DskipTests clean javadoc:javadoc install javadoc:aggregate

You will get a failure in the forked execution

[INFO] >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
[INFO] Forking Jenkins cli 2.123-SNAPSHOT
[INFO] >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
[INFO] 
[INFO] --- maven-enforcer-plugin:3.0.0-M1:display-info (display-info) @ cli ---
[INFO] Maven Version: 3.5.3
[INFO] JDK Version: 1.8.0_171 normalized as: 1.8.0-171
[INFO] OS Info: Arch: amd64 Family: unix Name: linux Version: 4.15.0-20-generic
[INFO] 
[INFO] --- maven-enforcer-plugin:3.0.0-M1:enforce (display-info) @ cli ---
[INFO] 
[INFO] --- maven-enforcer-plugin:3.0.0-M1:enforce (enforce-banned-dependencies) @ cli ---
[INFO] 
[INFO] --- maven-localizer-plugin:1.24:generate (default) @ cli ---
[INFO] 
[INFO] --- maven-remote-resources-plugin:1.5:process (default) @ cli ---
[INFO] 
[INFO] --- maven-resources-plugin:3.0.2:resources (default-resources) @ cli ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 11 resources
[INFO] Copying 1 resource
[INFO] 
[INFO] --- flatten-maven-plugin:1.0.1:flatten (flatten) @ cli ---
[INFO] Generating flattened POM of project org.jenkins-ci.main:cli:jar:2.123-SNAPSHOT...
[INFO] 
[INFO] --- maven-compiler-plugin:3.6.2:compile (default-compile) @ cli ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 16 source files to …/cli/target/classes
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] …/cli/target/target/generated-sources/localizer/hudson/cli/client/Messages.java:[20,7] error: duplicate class: hudson.cli.client.Messages
[INFO] 1 error

[jglick]

FTR this reverts part of jglick@03fb71f from 2009:

modified to do aggregated javadoc and publish that

which was referenced from some long-gone publishing scripts. I have no visibility into what javadoc.jenkins.io is loaded from.

[jglick]

AFAICT this code just uses the core Javadoc JAR which should have been published without the aggregate goal, as indeed happened here, so I hope this change merely drops a chunk of work from the release which was being thrown out anyway.