HDDS-12130. Improve assertion compatibility with old Hadoop

[adoroszlai]

What changes were proposed in this pull request?

Assertions.assertThat is overloaded, returning different assertion object depending on the argument. Passing an instance of raw Comparable results in compile error. Hadoop's Path used to implement raw Comparable before it was parameterized in HADOOP-16196. Thus, compiling Ozone with old Hadoop that does not have HADOOP-16196 fails.

[ERROR] hadoop-ozone/integration-test/src/test/java/org/apache/hadoop/fs/contract/AbstractContractGetFileStatusTest.java:[404,13] cannot find symbol
  symbol:   method isEqualTo(org.apache.hadoop.fs.Path)
  location: class java.lang.Object

This can be improved by using more specific assertion factory method (e.g. assertThatObject).

https://issues.apache.org/jira/browse/HDDS-12130

How was this patch tested?

CI:
https://github.com/adoroszlai/ozone/actions/runs/12929097463

[nandakumar131]

Thanks @adoroszlai for finding and fixing this!

[adoroszlai]

Thanks @nandakumar131 for reviewing and merging it.