Bug fixes:

• [api] Do not create observability model by default (#11476 by rtribotte)
• [fastproxy] Fix content-length header assertion (#11498 by kevinpollet)
• [fastproxy] Handle responses without content length header (#11458 by rtribotte)
• [k8s/crd,k8s] Add missing headerField in Middleware CRD (#11499 by jspdown)
• [tracing,accesslogs] Bring back TraceID and SpanID fields in access logs (#11450 by rtribotte)

Misc:

• Merge branch v2.11 into v3.3 (#11502 by rtribotte)
• Merge branch v2.11 into v3.3 (#11491 by rtribotte)