Remove updating CHANGELOG step in release workflow (#4273) (#4280)

Co-authored-by: Leighton Chen <lechen@microsoft.com>

Clean cherry-pick of #4273 to the release/v1.28.x-0.49bx branch.

Part of #4281

.github/workflows/release.yml

@@ -129,80 +129,3 @@ jobs:
                             --notes-file /tmp/release-notes.txt \
                             --discussion-category announcements \
                             v$STABLE_VERSION
-
-      - uses: actions/checkout@v4
-        with:
-          # the step below is creating a pull request against main
-          ref: main
-
-      - name: Copy change log updates to main
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        run: |
-          if [[ -z $PRIOR_VERSION_WHEN_PATCH ]]; then
-            # this was not a patch release, so the version exists already in the CHANGELOG.md
-
-            # update the release date
-            date=$(gh release view v$STABLE_VERSION --json publishedAt --jq .publishedAt | sed 's/T.*//')
-            sed -Ei "s/## Version ${STABLE_VERSION}\/${UNSTABLE_VERSION} .*/## Version ${STABLE_VERSION}\/${UNSTABLE_VERSION} ($date)/" CHANGELOG.md
-
-            # the entries are copied over from the release branch to support workflows
-            # where change log entries may be updated after preparing the release branch
-
-            # copy the portion above the release, up to and including the heading
-            sed -n "0,/^## Version ${STABLE_VERSION}\/${UNSTABLE_VERSION} ($date)/p" CHANGELOG.md > /tmp/CHANGELOG.md
-
-            # copy the release notes
-            cat /tmp/CHANGELOG_SECTION.md >> /tmp/CHANGELOG.md
-
-            # copy the portion below the release
-            sed -n "0,/^## Version ${STABLE_VERSION}\/${UNSTABLE_VERSION} /d;0,/^## Version /{/^## Version/!d};p" CHANGELOG.md \
-              >> /tmp/CHANGELOG.md
-
-            # update the real CHANGELOG.md
-            cp /tmp/CHANGELOG.md CHANGELOG.md
-          else
-            # this was a patch release, so the version does not exist already in the CHANGELOG.md
-
-            # copy the portion above the top-most release, not including the heading
-            sed -n "0,/^## Version /{ /^## Version /!p }" CHANGELOG.md > /tmp/CHANGELOG.md
-
-            # add the heading
-            date=$(gh release view v$STABLE_VERSION --json publishedAt --jq .publishedAt | sed 's/T.*//')
-            echo "## Version ${STABLE_VERSION}/${UNSTABLE_VERSION} ($date)" >> /tmp/CHANGELOG.md
-
-            # copy the release notes
-            cat /tmp/CHANGELOG_SECTION.md >> /tmp/CHANGELOG.md
-
-            # copy the portion starting from the top-most release
-            sed -n "/^## Version /,\$p" CHANGELOG.md >> /tmp/CHANGELOG.md
-
-            # update the real CHANGELOG.md
-            cp /tmp/CHANGELOG.md CHANGELOG.md
-          fi
-
-      - name: Use CLA approved github bot
-        run: .github/scripts/use-cla-approved-github-bot.sh
-
-      - name: Create pull request against main
-        env:
-          # not using secrets.GITHUB_TOKEN since pull requests from that token do not run workflows
-          GITHUB_TOKEN: ${{ secrets.OPENTELEMETRYBOT_GITHUB_TOKEN }}
-        run: |
-          message="Copy change log updates from $GITHUB_REF_NAME"
-          body="Copy log updates from \`$GITHUB_REF_NAME\`."
-          branch="opentelemetrybot/copy-change-log-updates-from-${GITHUB_REF_NAME//\//-}"
-
-          if [[ -z $PRIOR_VERSION_WHEN_PATCH ]]; then
-            if git diff --quiet; then
-              echo there are no updates needed to the change log on main, not creating pull request
-              exit 0 # success
-            fi
-          fi
-
-          git commit -a -m "$message"
-          git push origin HEAD:$branch
-          gh pr create --title "$message" \
-                       --body "$body" \
-                       --head $branch \
-                       --base main