Make test conditional using RequiresFlagsEnabled and SdkSuppress

Earlier, NoSuchMethodException was preventing this from working. Setting the test sdk_version to test_current fixes the issue.

Bug: 432690258
Test: atest TextClassifierServiceTest
Flag: EXEMPT (bugfix)

Change-Id: Ifd24c4dff07780abdc334e4531d6fefebbe6e17c