RFR: build: top-level gradle do not need images

[Erik Helin]

Hi all,

please remove this little clean-up after de5c089d7b219b4efa0fa38f467e3db553d6c1b5. The top-level build does not need to use the `images` plugin, that line was only added for debugging purposes and should be removed.

Thanks,
Erik

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Commit messages:
 - build: top-level gradle do not need images

Changes: https://git.openjdk.java.net/skara/pull/1005/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1005&range=00
  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/skara/pull/1005.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1005/head:pull/1005

PR: https://git.openjdk.java.net/skara/pull/1005