[LANG-1808] remove redundant test case in CharSetUtilsTest.testDelete_StringStringarray

[IcoreE]

The unit test method testDelete_StringStringarray() in CharSetUtilsTest contains a redundant assertion

        assertEquals("hello", CharSetUtils.delete("hello", ""));
        assertEquals("hello", CharSetUtils.delete("hello", ""));

[garydgregory]

@IcoreE
You don't need to create Jira tickets for trivial changes.
TY!

[IcoreE]

Okay, I'll be more careful with this from now on. Thanks for reminding me. @garydgregory

[garydgregory]

Jira is https://issues.apache.org/jira/browse/LANG-1808