HDDS-10725. TestContentGenerator#writeWithHsync fails with Java 17

[adoroszlai]

What changes were proposed in this pull request?

Fix test failure with Java 17:

[ERROR] Tests run: 6, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.323 s <<< FAILURE! - in org.apache.hadoop.ozone.freon.TestContentGenerator
[ERROR] org.apache.hadoop.ozone.freon.TestContentGenerator.writeWithHsync  Time elapsed: 0.294 s  <<< ERROR!
java.lang.NullPointerException: Cannot read the array length because "this.buf" is null
	at java.base/java.io.ByteArrayOutputStream.ensureCapacity(ByteArrayOutputStream.java:97)
	at java.base/java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:130)
	at org.apache.hadoop.ozone.freon.ContentGenerator.write(ContentGenerator.java:98)
	at org.apache.hadoop.ozone.freon.TestContentGenerator.writeWithHsync(TestContentGenerator.java:113)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)

Switching to mockito-inline fixes the problem (related issue 1, 2).

https://issues.apache.org/jira/browse/HDDS-10725

How was this patch tested?

Tested with Java 17:

JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64 \
  ./hadoop-ozone/dev-support/checks/junit.sh \
  -am -pl :ozone-tools -Dtest='TestContentGenerator'
[INFO] Tests run: 6, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.614 s - in org.apache.hadoop.ozone.freon.TestContentGenerator

Regular CI:
https://github.com/adoroszlai/ozone/actions/runs/8764901899

[smengcl]

Thanks @adoroszlai !

[adoroszlai]

Thanks @smengcl for the review.