fix(android template): drop orphaned file provider authority variable

[zyniq82]

This re-instates what was done in 94b72cc, undone in e048d2b and later "fixed" in 1642584, which orphaned the fileprovider_authority variable in strings.xml.

As I'm not an Android developer, I'm not sure if the proper fix is to do what I just did now, re-instating the reference to the fileprovider_authority variable, or if it's better to keep AndroidManifest.xml unchanged and instead just remove the fileprovider_authority variable from strings.xml.

[jcesarmobile]

I think it's better to remove the fileprovider_authority from strings.xml as is unused.
Having ${applicationId} in the AndroidManifest.xml is better as it will pick changes on the application id without changing anything else.

[zyniq82]

I've updated as requested, so now the only change is simply dropping the orphaned fileprovider_authority variable from strings.xml.

I've also updated the pull request title to better reflect the change.

[jcesarmobile]

Perfect, thanks!