Don't include Bing entry in generated configurations

[simonpoole]

For discussion: ELI contains a dummy entry for Bing that even in the best of all scenarios can only be used to create an actual entry by duplicating it and adding a proper URL and even then it still needs hardwired special treatment to retrieve the meta data from Bing, with other words it is silly to include it in actual configuration files.

See https://github.com/MarcusWolschon/osmeditor4android/issues/1662 for a problem this is creating.

[bhousel]

From what I remember the dummy entries are more used for translation string sources than as actual imagery sources.
But yeah this index should support the dummy sources better, maybe with a dedicated type and skip the url template.