build(java): switch to release-please for release tagging (#442)

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.github/release-please.yml

@@ -1,2 +1,3 @@
+bumpMinorPreMajor: true
+handleGHRelease: true
 releaseType: java-yoshi
-bumpMinorPreMajor: true

synth.metadata

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-core.git",
-        "sha": "db5dcdeda126258465ef85e0ed4f66e6320a63d3"
+        "sha": "c282c378e204b42e895d73f68a3c2d56a5da30d1"
       }
     },
     {