feat(sli gitaly): stop ignoring Unavailable

What

Stop ignoring Unavailable for SSHUploadPackWithSidechannel, PostUploadPackWithSidechannel, ListBranchNamesContainingCommit gRPC methods.

Why

In gitlab-org/gitaly!5084 (merged) we've changed the gRPC status code from Unavailable to ResourceExhausted.

In https://log.gprd.gitlab.net/goto/3c6d5030-7215-11ed-85ed-e7557b0a598c we can see SSHUploadPackWithSidechannel is no longer returning Unavailable for maximum time in concurrency queue reached, but for other legit errors like Fail to transfer git data: stream closed and exit status 128 which might be legit issues that we've been ignoring.

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We can also see the change from Unavailable to ResourceExhausted

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Reference: https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/16844 Signed-off-by: Steve Azzopardi sazzopardi@gitlab.com