Fix randomness for correlation IDs
Followup for !80 (merged).
In gitaly!2746 (merged) I'm trying to update Gitaly to use new functionality from !80 (merged) but ran into an issue where IDs are not random enough. In fact, they are identical if generated within one millisecond if my reading of code is correct. See https://gitlab.com/gitlab-org/gitaly/-/jobs/828950527#L2008:
=== RUN TestGetCorrelationID/not_provided_in_context
TestGetCorrelationID/not_provided_in_context: gitalyssh_test.go:56:
Error Trace: gitalyssh_test.go:56
Error: Should not be: "01EP8TTJK00000000000000000"
Test: TestGetCorrelationID/not_provided_in_context
Messages: it should return a new correlation_id each time as it is not injected into the context
This MR sets a randomness source to use by the ULID library.
Edited by Mikhail Mazurskiy