This release includes internal changes to the service discovery system,
especially when discovering control plane components (like the
destination and identity controllers). Now, the proxy attempts to
balance requests across all pods in each control plane service. This
requires control plane changes to use "headless" services so that SRV
records are exposed. When the control plane services have a `clusterIP`
set, the proxy falls back to using normal A-record lookups.

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* tracing: add richer verbose spans to http clients (linkerd/linkerd2-proxy#622)
* trace: update tracing dependencies (linkerd/linkerd2-proxy#623)
* Remove `Resolution` trait (linkerd/linkerd2-proxy#606)
* Update proxy-identity to edge-20.8.2 (linkerd/linkerd2-proxy#627)
* Add build arg for skipping identity wrapper (linkerd/linkerd2-proxy#624)
* Wait for proxy thread to terminate in integration tests (linkerd/linkerd2-proxy#625)
* Remove scrubbing for unused headers (linkerd/linkerd2-proxy#628)
* Split orig-proto tests out of discovery tests (linkerd/linkerd2-proxy#629)
* Re-enable outbound timeout test (linkerd/linkerd2-proxy#630)
* profiles: perform profile resolution for IP addresses (linkerd/linkerd2-proxy#626)
* Move resolve api to async-stream (linkerd/linkerd2-proxy#599)
* Decouple discovery buffering from endpoint conversion (linkerd/linkerd2-proxy#631)
* resolve: Add a Reset state (linkerd/linkerd2-proxy#633)
* resolve: Eagerly fail resolutions (linkerd/linkerd2-proxy#634)
* test: replace `net2` dependency with `socket2` (linkerd/linkerd2-proxy#635)
* dns: Run DNS resolutions on the main runtime (linkerd/linkerd2-proxy#637)
* Load balance requests to the control plane (linkerd/linkerd2-proxy#594)
* Unify control plane client construction (linkerd/linkerd2-proxy#638)