chore: pick up changes from synthtool. (#1575)

* chore(java): remove readme autosynth job config

README generation is now handled by owlbot

Source-Author: Jeff Ching <chingor@google.com>
Source-Date: Wed Sep 8 12:11:28 2021 -0700
Source-Repo: googleapis/synthtool
Source-Sha: df5093b950d4aafd49a4c7758d74c44485263ada
Source-Link: googleapis/synthtool@df5093b

* chore: remove readme synth.py config

Source-Author: Jeff Ching <chingor@google.com>
Source-Date: Wed Sep 8 13:23:41 2021 -0700
Source-Repo: googleapis/synthtool
Source-Sha: 2d31a9243781b282202b4f76dc7bbc8b45803196
Source-Link: googleapis/synthtool@2d31a92

* chore: add gcf-owl-bot to list of trusted contributors

Source-Author: Jeff Ching <chingor@google.com>
Source-Date: Wed Sep 8 13:42:12 2021 -0700
Source-Repo: googleapis/synthtool
Source-Sha: a6b97202771f89a4b76873d43ea9a07d7fc95f91
Source-Link: googleapis/synthtool@a6b9720

.github/trusted-contribution.yml

@@ -1,2 +1,3 @@
 trustedContributors:
-- renovate-bot
+- renovate-bot
+- gcf-owl-bot[bot]

synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigquery.git",
-        "sha": "b0e5d7ade8a82680cb02050586b758b83b80632e"
+        "sha": "466c2953a38071d47abaa25e4a5b7470e6c38f8e"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "17ee6e5c08f2eb47029beee4776ce990e56b3925"
+        "sha": "a6b97202771f89a4b76873d43ea9a07d7fc95f91"
       }
     }
   ],
@@ -23,7 +23,6 @@
     ".github/PULL_REQUEST_TEMPLATE.md",
     ".github/blunderbuss.yml",
     ".github/generated-files-bot.yml",
-    ".github/readme/synth.py",
     ".github/release-please.yml",
     ".github/release-trigger.yml",
     ".github/snippet-bot.yml",
@@ -40,7 +39,6 @@
     ".kokoro/common.sh",
     ".kokoro/continuous/common.cfg",
     ".kokoro/continuous/java8.cfg",
-    ".kokoro/continuous/readme.cfg",
     ".kokoro/nightly/common.cfg",
     ".kokoro/nightly/integration.cfg",
     ".kokoro/nightly/java11.cfg",