HADOOP-19127. Do not run unit tests on Windows pre-commit CI (#6672)

dev-support/bin/hadoop.sh

@@ -387,6 +387,11 @@ function personality_modules
       fi
     ;;
     unit)
+      if [[ "$IS_WINDOWS" && "$IS_WINDOWS" == 1 && (-z "$IS_NIGHTLY_BUILD" || "$IS_NIGHTLY_BUILD" == 0) ]]; then
+        echo "Won't run unit tests for Windows in pre-commit CI"
+        return
+      fi
+
       extra="-Dsurefire.rerunFailingTestsCount=2"
       if [[ "${BUILDMODE}" = full ]]; then
         ordering=mvnsrc