chore: Remove obsolete files (#6573)

* chore: remove obsolete kokoro release configs

* update owlbot.py

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* fix merge conflicts

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: alicejli

.github/workflows/approve-readme.yaml

@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-latest
     if: github.repository_owner == 'googleapis' && github.head_ref == 'autosynth-readme'
     steps:
-      - uses: actions/github-script@v7
+      - uses: actions/github-script@v6
         with:
           github-token: ${{secrets.YOSHI_APPROVER_TOKEN}}
           script: |

.github/workflows/ci.yaml

@@ -27,8 +27,8 @@ jobs:
       matrix:
         java: [11, 17, 21]
     steps:
-    - uses: actions/checkout@v4
-    - uses: actions/setup-java@v4
+    - uses: actions/checkout@v3
+    - uses: actions/setup-java@v3
       with:
         distribution: temurin
         java-version: ${{matrix.java}}
@@ -41,8 +41,8 @@ jobs:
     name: "units (8)"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-java@v4
+      - uses: actions/checkout@v3
+      - uses: actions/setup-java@v3
         with:
           java-version: 8
           distribution: temurin
@@ -51,7 +51,7 @@ jobs:
         # https://maven.apache.org/surefire/maven-surefire-plugin/test-mojo.html#jvm
         run: echo "SUREFIRE_JVM_OPT=-Djvm=${JAVA_HOME}/bin/java" >> $GITHUB_ENV
         shell: bash
-      - uses: actions/setup-java@v4
+      - uses: actions/setup-java@v3
         with:
           java-version: 17
           distribution: temurin
@@ -63,8 +63,8 @@ jobs:
     steps:
     - name: Support longpaths
       run: git config --system core.longpaths true
-    - uses: actions/checkout@v4
-    - uses: actions/setup-java@v4
+    - uses: actions/checkout@v3
+    - uses: actions/setup-java@v3
       with:
         distribution: temurin
         java-version: 8
@@ -78,8 +78,8 @@ jobs:
       matrix:
         java: [17]
     steps:
-    - uses: actions/checkout@v4
-    - uses: actions/setup-java@v4
+    - uses: actions/checkout@v3
+    - uses: actions/setup-java@v3
       with:
         distribution: temurin
         java-version: ${{matrix.java}}
@@ -88,8 +88,8 @@ jobs:
   javadoc:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
-    - uses: actions/setup-java@v4
+    - uses: actions/checkout@v3
+    - uses: actions/setup-java@v3
       with:
         distribution: temurin
         java-version: 17
@@ -100,8 +100,8 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
-    - uses: actions/setup-java@v4
+    - uses: actions/checkout@v3
+    - uses: actions/setup-java@v3
       with:
         distribution: temurin
         java-version: 11
@@ -112,8 +112,8 @@ jobs:
   clirr:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
-    - uses: actions/setup-java@v4
+    - uses: actions/checkout@v3
+    - uses: actions/setup-java@v3
       with:
         distribution: temurin
         java-version: 8

.github/workflows/renovate_config_check.yaml

@@ -14,7 +14,7 @@ jobs:
       uses: actions/checkout@v4
 
     - name: Set up Node.js
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v3
       with:
         node-version: '20'