build(java): update autorelease title check in response to the new multi release branch changes (#401)

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Synth log will be available here:
https://source.cloud.google.com/results/invocations/50a12256-ca5e-4f80-a8f2-ba3c4ab12a2c/targets

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Source-Link: googleapis/synthtool@0b064d7

Author: yoshi-automation

java-core/.github/workflows/auto-release.yaml

@@ -16,8 +16,8 @@ jobs:
             return;
           }
 
-          // only approve PRs like "chore(master): release <release version>"
-          if ( !context.payload.pull_request.title.startsWith("chore(master): release") ) {
+          // only approve PRs like "chore: release <release version>"
+          if ( !context.payload.pull_request.title.startsWith("chore: release") ) {
             return;
           }
 

java-core/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-core.git",
-        "sha": "aa8bd6743cf3712e0a6312ce5de8bc96c41c157d"
+        "sha": "70f3a5073dc63236f45fd06bd2cc4a044a43c35f"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "d0bdade9a962042dc0f770cf631086f3db59b5b0"
+        "sha": "0b064d767537e0675fc053e53fca473c5c701fb8"
       }
     }
   ],