gitserver: initialize logger on gitservice.Handler
Created by: bobheadxi
Forgot to push this to https://github.com/sourcegraph/sourcegraph/pull/36259, which makes this required
Test plan
n/a, checked for all remaining references: https://sourcegraph.com/github.com/sourcegraph/sourcegraph@382fe4753336d6d3fb4eb87a8f2d925b06ea4fb1/-/blob/lib/gitservice/gitservice.go?L42%3A6=#tab=references
Also sg start