HDDS-12807. Clean up TestKeyManagerImpl unit test

[echonesis]

What changes were proposed in this pull request?

This PR cleans up TestKeyManagerImpl by replacing the long parameter lists in the parameterized table iterator tests with a small TableIteratorTestCase builder.
The change also separates successful and invalid table iterator cases, so the expected exception path is tested explicitly instead of being mixed into the common assertion flow.

Generated-by: OpenAI Codex (GPT-5)

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-12807

How was this patch tested?

Tested with:

mvn clean test -pl :ozone-manager -am \
  -Dtest=TestKeyManagerImpl \
  -DskipShade -DskipRecon -DskipDocs

GitHub Actions CI: https://github.com/echonesis/ozone/actions/runs/28430712787

[adoroszlai]

Thanks @echonesis for the patch. Overall LGTM, few minor improvements suggested.

[adoroszlai]

This lets us avoid the need for SuppressWarnings("unchecked"):

Suggested change

	V value = valueClass == String.class ? (V) key : mock(valueClass);
	V value = valueClass == String.class ? valueClass.cast(key) : mock(valueClass);

[adoroszlai]

Class 'TableIteratorTestCase' is exposed outside its defined visibility scope

Suggested change

	public void testGetDeletedKeyEntries(TableIteratorTestCase testCase) throws IOException {
	void testGetDeletedKeyEntries(TableIteratorTestCase testCase) throws IOException {

Also applies to other parameterized test methods.

Since JUnit 5, test methods do not need to be public. It's better to keep them package-private for simplicity/brevity regardless of this warning.

[adoroszlai]

Mockito.mock is already imported

Suggested change

	OMMetadataManager metadataManager = Mockito.mock(OMMetadataManager.class);
	OMMetadataManager metadataManager = mock(OMMetadataManager.class);

Also in few other places.

[adoroszlai]

nit: class can be renamed to TestCase since it's private