fix(scale-telekom-header): fix no service links breaks component

[niklaswa]

When using the scale-telekom-header with a profile menu with no service links and hideLoginSettings set to true, the component will crash as the serviceLinks property is undefined.

Example:

<scale-telekom-header type="slim">
    <scale-telekom-nav-list variant="functions" slot="functions" scrolled>
        <scale-telekom-profile-menu
            hide-login-settings="true"
            login-url="/login"
            logged-in="true"
            label="Niklas"
            logout-label="Logout"
            logout-url="/logout"
        ></scale-telekom-profile-menu>
    </scale-telekom-nav-list>
</scale-telekom-header>

This PR changes the serviceLinksEmpty method by introducing a preceding property check to see if the property is defined and then continues with the length check.

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[maomaoZH]

@niklaswa thanks for PR. LGTM

[maomaoZH]

@niklaswa would you please check the failed tests before you merge it to main? Thanks!

[niklaswa]

@niklaswa would you please check the failed tests before you merge it to main? Thanks!

Not really sure why this git check fails there to be honest. Maybe you can rerun the jobs? Doesn't look like a code issue for me at the moment

[amir-ba]

THis will be closed as it is added as part of 2339