Update bot branch names to conform with branch protection rules (#518)

similar to
open-telemetry/opentelemetry-java-instrumentation#6862

Author: trask

.github/workflows/backport.yml

@@ -33,7 +33,7 @@ jobs:
           commit=$(gh pr view $NUMBER --json mergeCommit --jq .mergeCommit.oid)
           title=$(gh pr view $NUMBER --json title --jq .title)
 
-          branch="backport-${NUMBER}-to-${GITHUB_REF_NAME//\//-}"
+          branch="opentelemetrybot/backport-${NUMBER}-to-${GITHUB_REF_NAME//\//-}"
 
           git cherry-pick $commit
           git push origin HEAD:$branch

.github/workflows/prepare-patch-release.yml

@@ -48,7 +48,7 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.BOT_TOKEN }}
         run: |
           message="Prepare release $VERSION"
-          branch="prepare-release-${VERSION}"
+          branch="opentelemetrybot/prepare-release-${VERSION}"
 
           git commit -a -m "$message"
           git push origin HEAD:$branch

.github/workflows/prepare-release-branch.yml

@@ -58,7 +58,7 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.BOT_TOKEN }}
         run: |
           message="Prepare release $VERSION"
-          branch="prepare-release-${VERSION}"
+          branch="opentelemetrybot/prepare-release-${VERSION}"
 
           git commit -a -m "$message"
           git push origin HEAD:$branch
@@ -107,7 +107,7 @@ jobs:
         run: |
           message="Update version to $NEXT_VERSION"
           body="Update version to \`$NEXT_VERSION\`."
-          branch="update-version-to-${NEXT_VERSION}"
+          branch="opentelemetrybot/update-version-to-${NEXT_VERSION}"
 
           git commit -a -m "$message"
           git push origin HEAD:$branch

.github/workflows/release.yml

@@ -245,7 +245,7 @@ jobs:
         run: |
           message="Copy change log updates from $GITHUB_REF_NAME"
           body="Copy log updates from \`$GITHUB_REF_NAME\`."
-          branch="copy-change-log-updates-from-${GITHUB_REF_NAME//\//-}"
+          branch="opentelemetrybot/copy-change-log-updates-from-${GITHUB_REF_NAME//\//-}"
 
           if [[ $VERSION == *.0 ]]; then
             if git diff --quiet; then