[17.05] Do not modify self.app.config.tool_data_path

[mvdbeek]

and self.app.config.tool_data_table_config_path during metadata setting.

xref galaxyproject/tools-iuc#1315.

I suspect multiple threads installing tool simultaneously may have led
to self.app.config.tool_data_path and/or
self.app.config.tool_data_table_config_path being set to a temporary
directory. Initial testing looks like this is not necessary.

[mvdbeek]

I have gone through the various functions that are being called by generate_metadata_for_changeset_revision , and none are relying on a modified self.app.config.tool_data_table_config_path / self.app.config.tool_data_path, so this should be a safe change. Installing a new data manager and associated tables also worked fine. This is ready for review now.

[martenson]

Thank you @mvdbeek !