couchdb-lucene: set default JAVA_HOME

[bayandin]

• Have you followed the guidelines for contributing?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing brew install <formula>)?

---

Otherwise, it fails with on CI: #66472 (comment)

==> brew test --retry --verbose couchdb-lucene
==> FAILED
==> Testing couchdb-lucene
/usr/bin/sandbox-exec -f /private/tmp/homebrew20201208-39832-1m0ogmc.sb ruby -W0 -I $LOAD_PATH -- /usr/local/Homebrew/Library/Homebrew/test.rb /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/couchdb-lucene.rb --verbose --retry
No Java runtime present, requesting install.

[BrewTestBot]

🤖 A scheduled task has triggered a merge.