chore: freeze OpenTelemetry at 1.24.0

[quartzmo]

• go.opentelemetry.io/otel 1.25.0 and submodules no longer support Go 1.20.
• Stop updating Open Telemetry until our runtime support catches up.

Got this error in vet in the latest google-cloud-go renovate PR #9724:

Error: ../../../[go/pkg/mod/](http://goto.google.com/pkg/mod/go.opentelemetry.io/otel)[go.opentelemetry.io/otel](http://go.opentelemetry.io/[email protected]/attribute/set.go:7:2)[@v1.25.0/attribute/set.go:7:2](http://go.opentelemetry.io/[email protected]/attribute/set.go:7:2): package cmp is not in GOROOT (/opt/hostedtoolcache/go/1.20.14/x64/src/cmp)
[1391](https://github.com/googleapis/google-cloud-go/actions/runs/8743459156/job/23994039449?pr=9724#step:5:1392)note: imported by a module that requires go 1.21 (compile)
[1392](https://github.com/googleapis/google-cloud-go/actions/runs/8743459156/job/23994039449?pr=9724#step:5:1393)Error: ../../../[go/pkg/mod/](http://goto.google.com/pkg/mod/go.opentelemetry.io/otel)[go.opentelemetry.io/otel](http://go.opentelemetry.io/[email protected]/attribute/set.go:10:2)[@v1.25.0/attribute/set.go:10:2](http://go.opentelemetry.io/[email protected]/attribute/set.go:10:2): package slices is not in GOROOT (/opt/hostedtoolcache/go/1.20.14/x64/src/slices)
[1393](https://github.com/googleapis/google-cloud-go/actions/runs/8743459156/job/23994039449?pr=9724#step:5:1394)note: imported by a module that requires go 1.21 (compile)