[Build] Remove obsolete build-scripts for ubunut-jikespg docker image

[HannesWell]

What it does

With eclipse-platform/eclipse.platform.releng.aggregator#2271 the removed scripts are not necessary anymore.

But in general I wonder if the build docker-image is even used at all? I could not find any references in the current build setup of JDT.
Unfortunately I also could not find the current number of recent pulls in Docker-Hub:

• https://hub.docker.com/layers/eclipse/platformreleng-ubuntu-gtk3-metacity/jikespg/images/sha256-1579f6b3286aca655e20c2dedf22d4eb38254ad413594c49093b61fb0f0857ad?context=explore

@akurtakov, @iloveeclipse, @jarthana or @sravanlakkimsetti could you help here or could tell who knows this?

Author checklist

• I have thoroughly tested my changes
• The change is following the coding conventions
• I have signed the Eclipse Contributor Agreement (ECA)

[stephan-herrmann]

The history of those files points to https://bugs.eclipse.org/576415

The background is this: generating our parser from the grammar file java.g involves an invocation of the parser generator jikespg, as explained in a bit detail on https://github.com/eclipse-jdt/eclipse.jdt.core/wiki/ECJ-Parse

Over time we had to fix a few bugs in that tool, as can be seen in https://github.com/jikespg/jikespg/tree/fixes-combined - Unfortunately, compiling this C program doesn't seem to be straight forward on windows machines. So when I change the grammar, I have no problem generating the parser (as I'm on linux), but @mpalat e.g. had issues with that.

Ergo, Manoj will tell you, if the solution with parser-generator-as-a-service has been used recently. Look at the history of java.g to find out who changed the grammar file in the past. All of them needed to invoke jikespg one way or other. @srikanth-sankaran I believe you have a recent / functioning jikespg on your machine, right?

[srikanth-sankaran]

I am on windows generally but use a Ubuntu VM for running jikespg. The parser generation service gave me some grief when I tried - don't remember the details.

[HannesWell]

Ergo, Manoj will tell you, if the solution with parser-generator-as-a-service has been used recently.

Thank you for your elaboration.
I just stumbled upon it and just wanted to make sure that this docker-image just lays around unused.

But regardless of if the image is used or not the files suggested for removal with this PR are obsolete and not used anymore.