Disable clang format for java

[owen-mc-diffblue]

This PR should disable clang-format for java. I don't think we are particularly prescriptive about our java style, and it's annoying when PRs fail because of a java formatting issue. I've cherry-picked #5068 which is currently failing for this reason to check that it works. I've marked it "Do not merge" until those two commits have been removed.

• Each commit message has a non-empty body, explaining why the change was made.
• Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[owen-mc-diffblue]

The clang-format job passed with #5068 cherry-picked (https://travis-ci.org/diffblue/cbmc/jobs/578725706), which confirms that this works. I stopped CI and removed those commits.

[allredj]

⚠️
This PR failed Diffblue compatibility checks (cbmc commit: 0d46406).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/125208912
Status will be re-evaluated on next push.
Common spurious failures include: the cbmc commit has disappeared in the mean time (e.g. in a force-push); the author is not in the list of contributors (e.g. first-time contributors); compatibility was already broken by an earlier merge.

[codecov-io]

Codecov Report

Merging #5069 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #5069   +/-   ##
========================================
  Coverage    69.54%   69.54%           
========================================
  Files         1315     1315           
  Lines       108959   108959           
========================================
  Hits         75775    75775           
  Misses       33184    33184

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[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: 74d1d6f).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/125419472

[owen-mc-diffblue]

Running clang-format on java was turned on in #4926, to stop clang-format from silently aborting. This PR makes it ignore java, rather than applying any reformatting to it, which is closer to what we were doing before (but without the problem of silently aborting).

[antlechner]

I keep forgetting to run clang-format on .java files and don't really like the current result of running it.
👍