Remove the changelog, simplify releases (grpc-ecosystem#2111)

Release v2.3.0

release: generate changelog for v2.2.0

Generate changelog for v2.1.0 (grpc-ecosystem#1887)

Generate changelog for v1.16.0 (grpc-ecosystem#1776)

The changelog is buggered but I don't think it's worth
trying to remedy manually.

Generate changelog for v2.0.1 (grpc-ecosystem#1770)

Generate changelog for v2.0.0 (grpc-ecosystem#1744)

* Update v1 renovate ignores.

* Reenable automerge

* Generate changelog for v2.0.0

Update dependency bazel_gazelle to v0.22.2

Update dependency bazel_gazelle to v0.22.2

Generate changelog for v2.0.0-beta.5