backport crdb 98422 GetConfReader freshness check - #75

control: job assigned to worker 01KX4DEV2QA0A9VQKC4S6QAEFJ [factory aws, i-06134927deb971ee2] (queued for 31 s)
...
task: starting task 0: "setup"
task: process exited: duration 19550 ms, exit code 0
...
task: starting task 1: "authentication"
task: process exited: duration 3 ms, exit code 0
...
task: starting task 2: "clone repository"
task: process exited: duration 33640 ms, exit code 0
...
task: starting task 3: "build"
...
| go: downloading github.com/gorilla/sessions v1.2.1
| go: downloading github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f
| go: downloading github.com/jmespath/go-jmespath/internal/testify v1.5.1
| go: downloading github.com/stretchr/objx v0.5.0
| go: downloading github.com/google/martian/v3 v3.2.1
| go: downloading github.com/gorilla/securecookie v1.1.1
| go: downloading github.com/jpillora/backoff v1.0.0
| go: downloading github.com/go-swagger/scan-repo-boundary v0.0.0-20180623220736-973b3573c01 [...]
| go: downloading github.com/google/martian v2.1.0+incompatible
| go: downloading github.com/tidwall/pretty v1.0.0
| go: downloading go.etcd.io/etcd v0.5.0-alpha.5.0.20200910180754-dd1b699fc489
| go: downloading go.uber.org/goleak v1.1.10
| go: downloading github.com/alecthomas/units v0.0.0-20210208195552-ff826a37aa15
| go: downloading github.com/prometheus/common/sigv4 v0.1.0
| go: downloading github.com/dennwc/varint v1.0.0
| go: downloading golang.org/x/lint v0.0.0-20210508222113-6edffad5e616
| + git diff --exit-code
| + (( !failed ))
task: process exited: duration 963792 ms, exit code 0
|W| found 0 output files