deprecate java_is_array_type

[kroening]

We've got a similar (but not identical) function. This one has no users.

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

[allredj]

✔️
Passed Diffblue compatibility checks (cbmc commit: 0c0ce3f).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/114904440

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (develop@891f04e). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             develop    #4769   +/-   ##
==========================================
  Coverage           ?    68.5%           
==========================================
  Files              ?     1275           
  Lines              ?   105017           
  Branches           ?        0           
==========================================
  Hits               ?    71942           
  Misses             ?    33075           
  Partials           ?        0

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 891f04e...0c0ce3f. Read the comment docs.