* content: fixed data race in IterateUnreferencedBlobs
* upload: fixed data race between uploader and estimator
* testing: fixed data race in repo/blob/logging test
* makefile: run tests on CI/linux/amd64 with -race
* robustness: fixed test race
* content: fixed data race getContentDataUnlocked that triggers TestParallelWrites - looks scary but in practice very hard to trigger in real life and does not cause data corruption
* testing: reduce test complexity under race detector
* server: fixed minor race in refreshStatus()
* testing: reduced depth of sharedTestDataDir2
* ci: run race detector in separate job
* ci: run unit test race detector in parallel to integration tests
9a756c719f