Run apt-get in docker builds without using any cache.

[daniellehrner]

PR description

The docker build step can fail if apt-get gets it's dependencies from a transparent cache (e.g. from an ISP) and this cache serves corrupted or outdated packages. This PR clears all the apt-get cache first and afterwards executes the next steps while making sure that no cache whatsoever is used.

I have further split the the RUN command into several steps to make debugging easier, because like that the exact command that is failing while be shown. Right now we have several commands chained together and it's not always clear which of the several commands was failing.

Fixed Issue(s)

fixes #7009

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• Checked out our contribution guidelines?
• Considered documentation and added the doc-change-required label to this PR if updates are required.
• Considered the changelog and included an update if required.
• For database changes (e.g. KeyValueSegmentIdentifier) considered compatibility and performed forwards and backwards compatibility tests

Locally, you can run these tests to catch failures early:

• unit tests: ./gradlew build
• acceptance tests: ./gradlew acceptanceTest
• integration tests: ./gradlew integrationTest
• reference tests: ./gradlew ethereum:referenceTests:referenceTests

[fab-10]

Which is the impact, of splitting the RUN command, in term of bigger image size?

[daniellehrner]

Which is the impact, of splitting the RUN command, in term of bigger image size?

@fab-10 I misunderstood how docker images are built and did not realize the impact in size of several run commands. I've reverted the change and use only one run command to save disk size.