[SPARK-29733][TESTS] Fix wrong order of parameters passed to assertEquals

[MaxGekk]

What changes were proposed in this pull request?

The assertEquals method of JUnit Assert requires the first parameter to be the expected value. In this PR, I propose to change the order of parameters when the expected value is passed as the second parameter.

Why are the changes needed?

Wrong order of assert parameters confuses when the assert fails and the parameters have special string representation. For example:

assertEquals(input1.add(input2), new CalendarInterval(5, 5, 367200000000L));

java.lang.AssertionError: 
Expected :interval 5 months 5 days 101 hours
Actual   :interval 5 months 5 days 102 hours

Does this PR introduce any user-facing change?

No

How was this patch tested?

By existing tests.

[SparkQA]

Test build #113161 has finished for PR 26377 at commit 86c1340.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[MaxGekk]

jenkins, retest this, please

[srowen]

Excellent, great fix. Looks good pending tests.

[SparkQA]

Test build #113179 has finished for PR 26377 at commit 86c1340.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[dongjoon-hyun]

+1, LGTM. Thank you, @MaxGekk and @srowen .
Merged to master.