The module name should not be passed as a hard-coded value

The module name should not be passed as a hard-coded value, since it is not a valid theme name. Refs. https://github.com/zikula/core/issues/1816

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| Refs tickets  | -
| License       | MIT
| Doc PR        | -
If you remove that hard-coded value, the code works fine. Also, if you scan other files in the core that clears the theme cache, you will see that it does not pass any value into getInstance, which results in the default user theme being populated. Nevertheless, it is still incorrect to pass in the name of the module. It needs to be a name of theme. If you look at the __construct for the theme view function, you will see that uses a theme name to query for results for theme attributes, theme variables, etc. "ZikulaThemeModule" is incorrect, cause it's not a theme name to do a valid query.