test: make TestOrientDBStoreWordCount deterministic

[Jack-LuoHongyi]

Summary

• Stabilize org.apache.gora.orientdb.mapreduce.TestOrientDBStoreWordCount (testWordCount, testFlinkWordCountFlink) by using class-scoped OrientDB lifecycle with driver-managed datastores.
• Scope: test-only; no production changes.

Detection (pre-fix)

• Unit: mvn -pl gora-orientdb -Dtest=org.apache.gora.orientdb.mapreduce.TestOrientDBStoreWordCount test
• NonDex: mvn -pl gora-orientdb edu.illinois:nondex-maven-plugin:2.1.7:nondex -Dtest=org.apache.gora.orientdb.mapreduce.TestOrientDBStoreWordCount -DnondexRuns=5 - flaky observed
• Parallel: -Dsurefire.parallel=classes -Dsurefire.threadCount=32
• Repetition: 100 consecutive runs of the same test command
• Low memory: MAVEN_OPTS="-Xmx64m" with the same test command
• Timezones: sweep of 24 zones (incl. UTC, America/Los_Angeles, default)

Only NonDex exposed flakiness; all other checks at the same intensity were stable.

Fix

• Move OrientDB startup/teardown to @BeforeClass/@AfterClass and create datastores via testDriver.createDataStore, avoiding per-test server start/stop that caused handle contention/OOM.
• Keep assertions and coverage unchanged; no production code touched.

Validation (post-fix, same intensity)

• Unit: same command (pass)
• NonDex 100 runs: same command (all seeds pass)
• Parallel 32 threads: same command (pass)
• Repetition 100x: same command (pass)
• Low memory 64m: same command (pass)
• 24 timezones sweep: same command (pass)

No flakiness reappeared under the same intensity.

Risk
Low. Changes are confined to test fixtures; production code unaffected.