background-portal: Stop sending app-id quoted

[sophie-h]

Since #696, the arguments sent to background portal implementations
contained the app-id in quoted form. Implementations, in turn, created
invalid autostart files.

[sophie-h]

While 28ec93c mentions

First parse the argv so it's unquoted then quote any arguments that need
it. Don't do so in the background portal since the backend handles it.

I think the commit misses excluding the app-id from quoting for the background portal.

[sophie-h]

Thanks for fixing the coding style!

[sophie-h]

@mleeds @GeorgesStavracas You authored/merged the original changes. Maybe you can have a look at this?

As I see it the implications of this bug are that, for example, background processes for scheduled backups are not started. IIRC the autostart file is never rewritten. That means if anyone sets up the app with 1.14.0 to 1.14.3 the autostart file might never get automatically fixed. Therefore it feels somewhat urgent for me to release this fix.

[GeorgesStavracas]

Please squash the second commit with the first one. LGTM otherwise.

[sophie-h]

Please squash the second commit with the first one. LGTM otherwise.

Done :)