By Supantha Mukherjee and Elizabeth Culliford (Reuters) – Spotify investors will focus on how much its ‘Netflix for audio’ strategy is costing the streaming service when it reports fourth-quarter results on Wednesday against the backdrop of several angry high-profile artists withdrawing their tracks. Over the past four years, Spotify has spent more than $1 billion on podcasts such as Joe Rogan’s in an attempt to triumph over rival music subscription services from Apple and Amazon. The decision by Neil Young and Joni Mitchell to pull their music from Spotify in protest over the views about COVI…