Fix flaky TestReload

[albertteoh]

Signed-off-by: albertteoh albert.teoh@logz.io

Which problem is this PR solving?

• Fixes Flaky test pkg/config/tlscfg/TestReload (cert_watcher_test.go) #2644 .

Short description of the changes

• The logs from Flaky test pkg/config/tlscfg/TestReload (cert_watcher_test.go) #2644 indicate a race condition where the cert.crt file was loaded before the key.crt file, which was not observed in local testing in Fix flaky TestReload #2624. That is "Loaded modified certificate" was logged for certFile.Name() before keyFile.Name().
• This PR fixes the race condition by being more explicit on the wait condition to include the keyFile.Name() in the log entry.

Testing

The following test run passes locally:

go test -test.count=5000 -test.run=TestReload$ ./pkg/config/tlscfg/

[yurishkuro]

We could merge this if the branch build is successful: https://travis-ci.org/github/albertteoh/jaeger/builds/745572554 (since our main build is out of credits)

[albertteoh]

We could merge this if the branch build is successful: https://travis-ci.org/github/albertteoh/jaeger/builds/745572554 (since our main build is out of credits)

Thanks @yurishkuro . It looks like the build has just passed.