resourceloader: Call setName() in test suite before calling getStyles()

resourceloader: Call setName() in test suite before calling getStyles()

This caused a database error due to NULL being inserted as name, which is illegal.

> Function: DatabaseSqlite::replace/single-row
> NOT NULL constraint failed: unittest_module_deps.md_module
> Stack trace:
> #3 includes/resourceloader/ResourceLoaderFileModule.php(420): DatabaseSqlite->replace()
> #4 tests/phpunit/includes/resourceloader/ResourceLoaderTest.php(88): ResourceLoaderFileModule->getStyles()
> #5 (): ResourceLoaderTest->testLessFileCompilation()

This test shouldn't be trigggering database updates, but that's for
a later change to stub out or refactor.

Bug: T91567
Change-Id: Ic451bd41e2ffc188d2efd6b7ce61b03b9de61296