Running x-pack/metricbeat system-tests fails because the 2017-GA tag does not exist anymore. Instead, it's been replaced with 2017-GA-ubuntu

• Docker Hub: https://hub.docker.com/_/microsoft-mssql-server
• See the available tags here: https://mcrflowprodcentralus.data.mcr.microsoft.com/mcrprod/mssql/server?P1=1624445408&P2=1&P3=1&P4=H4w0lWyvxuvd60C1%2B6N6XJO2pSitpSmMrnB%2F%2FNm%2BM0w%3D&se=2021-06-23T10%3A50%3A08Z&sig=OWwqxML5Kzr5xkrNZEK0HzpLS3YHYKEGjxU8bQgB%2F4w%3D&sp=r&sr=b&sv=2015-02-21

cc/ @jsoriano