Drop obsolete go.uber.org/automaxprocs

[timebertt]

What this PR does / why we need it:

With #625, automaxprocs should no longer be needed, see https://tip.golang.org/doc/go1.25#container-aware-gomaxprocs:

On Linux, the runtime considers the CPU bandwidth limit of the cgroup containing the process, if any. If the CPU bandwidth limit is lower than the number of logical CPUs available, GOMAXPROCS will default to the lower limit. In container runtime systems like Kubernetes, cgroup CPU bandwidth limits generally correspond to the “CPU limit” option. The Go runtime does not consider the “CPU requests” option.

Which issue(s) this PR fixes:
n/a

Special notes for your reviewer: