Update Sourcegraph Docker insiders images

[sourcegraph-bot]

This PR contains the following updates:

Package	Update	Change
index.docker.io/sourcegraph/cadvisor	digest	327b247 -> 9d03f7d
index.docker.io/sourcegraph/frontend	digest	995edf4 -> fe393f8
index.docker.io/sourcegraph/github-proxy	digest	e4c4126 -> a16db30
index.docker.io/sourcegraph/gitserver	digest	838f506 -> bd330ad
index.docker.io/sourcegraph/grafana	digest	31d3104 -> b4829e6
index.docker.io/sourcegraph/jaeger-agent	digest	7f22be6 -> 2be6cd9
index.docker.io/sourcegraph/jaeger-all-in-one	digest	914785f -> 12ed5cb
index.docker.io/sourcegraph/precise-code-intel-worker	digest	f22a3ff -> 1937ef1
index.docker.io/sourcegraph/prometheus	digest	ac6b667 -> 3dadba4
index.docker.io/sourcegraph/query-runner	digest	abb661e -> fe99c9d
index.docker.io/sourcegraph/repo-updater	digest	04ab321 -> 0f3cca1
index.docker.io/sourcegraph/searcher	digest	bf93849 -> 297555f
index.docker.io/sourcegraph/symbols	digest	9c7d4bc -> 4bf3780

Source: https://github.com/sourcegraph/sourcegraph/pull/15486

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