update other usages of alpine -> sourcegraph/alpine

Created by: slimsag

Move other usages of alpine to sourcegraph/alpine. See motivation in https://github.com/sourcegraph/sourcegraph/pull/13234

This does not affect behavior (or user) of the images at all it merely makes it more explicit when and where we are using root or not.

• Move cmd/server to use sourcegraph/alpine as its base image (but still use a root user). This means we don't need to install a number of dependencies which are already installed in sourcegraph/alpine.
• Improve documentation in server about why we aren't using a non-root user currently and link to tracking issue.
• Use sourcegraph/alpine in jaeger images (but still not using sourcegraph user, using the jaeger non-root user - which is kinda lame but at least its not root.)
• Use sourcegraph/alpine in resources-report and tracking-issue images for consistency and with intent to ban alpine from our codebase entirely in the near future. Also document that these are using a root user and that is a security risk (albeit incredibly low given we don't run those images / they run on github actions, but we should still avoid this for posterity sake.)

Helps #13035 (closed)