Upgrade all use of semconv to v1.21.0

[MrAlias]

Fix #4364

[codecov]

Codecov Report

Merging #4408 (6764e52) into main (196c1f0) will decrease coverage by 0.1%.
The diff coverage is 100.0%.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #4408     +/-   ##
=======================================
- Coverage   83.5%   83.5%   -0.1%     
=======================================
  Files        229     229             
  Lines      18645   18647      +2     
=======================================
  Hits       15578   15578             
- Misses      2749    2751      +2     
  Partials     318     318             

Files Changed	Coverage Δ
bridge/opentracing/internal/mock.go	67.0% <ø> (ø)
exporters/jaeger/jaeger.go	91.1% <ø> (ø)
exporters/otlp/otlpmetric/internal/otest/client.go	97.1% <ø> (ø)
...otlpmetric/otlpmetricgrpc/internal/otest/client.go	97.1% <ø> (ø)
...otlpmetric/otlpmetrichttp/internal/otest/client.go	97.1% <ø> (ø)
exporters/zipkin/model.go	94.7% <ø> (ø)
sdk/resource/builtin.go	90.3% <ø> (ø)
sdk/resource/container.go	92.3% <ø> (ø)
sdk/resource/env.go	94.0% <ø> (ø)
sdk/resource/host_id.go	97.4% <ø> (ø)
... and 3 more

... and 1 file with indirect coverage changes

[pellared]

Approving as I do not find my comment as a blocker.

PS. I have forgotten to "add" my comment 🤦 Adding now...