[BUG] License header is not being written to test classes

[dbwiddis]

What is the bug?

Test classes have no license header, or the old one not updated by #194

The paths implemented in #51 only include src/main/java.

How can one reproduce the bug?

1. Run spotless.
2. Observe no change in license headers in src/test/java

What is the expected behavior?

License headers match src/test/main and the template.

[dbwiddis]

Clearly whoever implemented this should never be allowed to commit to this repo again:

opensearch-sdk-java/gradle/formatting.gradle

Lines 32 to 35 in 6df1fa4

	format("license", {
	licenseHeaderFile("${rootProject.file("formatter/license-header.txt")}", "package ");
	target("src/main/java/**/*.java")
	})

Easy add of another line including test...