chore: create LTS branch 2.60.x

Author: jinseopkim0

.github/release-please.yml

@@ -79,5 +79,12 @@ branches:
       - >-
         google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/Version.java
     branch: 2.61.x
+  - bumpMinorPreMajor: true
+    handleGHRelease: true
+    releaseType: java-backport
+    extraFiles:
+      - >-
+        google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/Version.java
+    branch: 2.60.x
 extraFiles:
   - google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/Version.java

.github/sync-repo-settings.yaml

@@ -197,6 +197,26 @@ branchProtectionRules:
       - conformance
       - library_generation
       - unmanaged_dependency_check
+  - pattern: 2.60.x
+    isAdminEnforced: true
+    requiredApprovingReviewCount: 1
+    requiresCodeOwnerReviews: true
+    requiresStrictStatusChecks: false
+    requiredStatusCheckContexts:
+      - dependencies (17)
+      - lint
+      - clirr
+      - units (8)
+      - units (11)
+      - 'Kokoro - Test: Integration'
+      - cla/google
+      - 'Kokoro - Test: Java GraalVM Native Image A'
+      - 'Kokoro - Test: Java GraalVM Native Image B'
+      - 'Kokoro - Test: Java GraalVM Native Image C'
+      - javadoc
+      - conformance
+      - library_generation
+      - unmanaged_dependency_check
 permissionRules:
   - team: yoshi-admins
     permission: admin