chore: regenerate common templates (#248)

* changes without context

        autosynth cannot find the source of changes triggered by earlier changes in this
        repository, or by version upgrades to tools such as linters.

* chore(java): enable generated-files-bot

This bot will comment on pull requests that modify templated files. For java, we configure to read from our 2 synth.metadata files: (primary templates and README)

Source-Author: Jeff Ching <chingor@google.com>
Source-Date: Fri Oct 30 14:22:02 2020 -0700
Source-Repo: googleapis/synthtool
Source-Sha: b19b401571e77192f8dd38eab5fb2300a0de9324
Source-Link: googleapis/synthtool@b19b401

.github/CODEOWNERS

@@ -4,7 +4,9 @@
 # For syntax help see:
 # https://help.github.com/en/github/creating-cloning-and-archiving-repositories/about-code-owners#codeowners-syntax
 
+# The @googleapis/api-spanner-java is the default owner for changes in this repo
 *                       @googleapis/yoshi-java @googleapis/api-spanner-java
+**/*.java               @googleapis/api-spanner-java
 
 # The java-samples-reviewers team is the default owner for samples changes
 samples/**/*.java       @googleapis/java-samples-reviewers

.github/generated-files-bot.yml

@@ -0,0 +1,7 @@
+externalManifests:
+- type: json
+  file: 'synth.metadata'
+  jsonpath: '$.generatedFiles[*]'
+- type: json
+  file: '.github/readme/synth.metadata/synth.metadata'
+  jsonpath: '$.generatedFiles[*]'

synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-spanner-jdbc.git",
-        "sha": "66fc72c1ae967bf7608000c1f008f83c55cd8ab5"
+        "sha": "bdb6d483070018d5b6dac31bbf68ab66bfad5225"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "f68649c5f26bcff6817c6d21e90dac0fc71fef8e"
+        "sha": "b19b401571e77192f8dd38eab5fb2300a0de9324"
       }
     }
   ],
@@ -21,6 +21,7 @@
     ".github/ISSUE_TEMPLATE/feature_request.md",
     ".github/ISSUE_TEMPLATE/support_request.md",
     ".github/PULL_REQUEST_TEMPLATE.md",
+    ".github/generated-files-bot.yml",
     ".github/readme/synth.py",
     ".github/release-please.yml",
     ".github/snippet-bot.yml",