ci(spanner): clean up unused kokoro configurations

README.md

@@ -706,7 +706,6 @@ Java Version | Status
 ------------ | ------
 Java 8 | [![Kokoro CI][kokoro-badge-image-2]][kokoro-badge-link-2]
 Java 8 OSX | [![Kokoro CI][kokoro-badge-image-3]][kokoro-badge-link-3]
-Java 8 Windows | [![Kokoro CI][kokoro-badge-image-4]][kokoro-badge-link-4]
 Java 11 | [![Kokoro CI][kokoro-badge-image-5]][kokoro-badge-link-5]
 
 Java is a registered trademark of Oracle and/or its affiliates.

owlbot.py

@@ -31,12 +31,8 @@
         ".kokoro/nightly/samples.cfg",
         ".kokoro/build.bat",
         ".kokoro/presubmit/common.cfg",
-        ".kokoro/presubmit/java8-samples.cfg",
-        ".kokoro/presubmit/java11-samples.cfg",
-        ".kokoro/presubmit/samples.cfg",
         ".kokoro/presubmit/graalvm-native.cfg",
         ".kokoro/presubmit/graalvm-native-17.cfg",
-        ".kokoro/release/common.cfg",
         "samples/install-without-bom/pom.xml",
         "samples/snapshot/pom.xml",
         "samples/snippets/pom.xml",

synth.metadata

@@ -68,41 +68,16 @@
     ".kokoro/coerce_logs.sh",
     ".kokoro/common.cfg",
     ".kokoro/common.sh",
-    ".kokoro/continuous/java8.cfg",
     ".kokoro/dependencies.sh",
     ".kokoro/nightly/integration.cfg",
     ".kokoro/nightly/java11.cfg",
-    ".kokoro/nightly/java7.cfg",
     ".kokoro/nightly/java8-osx.cfg",
-    ".kokoro/nightly/java8-win.cfg",
     ".kokoro/nightly/java8.cfg",
     ".kokoro/populate-secrets.sh",
-    ".kokoro/presubmit/clirr.cfg",
     ".kokoro/presubmit/dependencies.cfg",
     ".kokoro/presubmit/graalvm-native.cfg",
     ".kokoro/presubmit/integration.cfg",
     ".kokoro/presubmit/java11.cfg",
-    ".kokoro/presubmit/java7.cfg",
-    ".kokoro/presubmit/java8-osx.cfg",
-    ".kokoro/presubmit/java8-win.cfg",
-    ".kokoro/presubmit/java8.cfg",
-    ".kokoro/presubmit/linkage-monitor.cfg",
-    ".kokoro/presubmit/lint.cfg",
-    ".kokoro/release/bump_snapshot.cfg",
-    ".kokoro/release/common.cfg",
-    ".kokoro/release/common.sh",
-    ".kokoro/release/drop.cfg",
-    ".kokoro/release/drop.sh",
-    ".kokoro/release/promote.cfg",
-    ".kokoro/release/promote.sh",
-    ".kokoro/release/publish_javadoc.cfg",
-    ".kokoro/release/publish_javadoc.sh",
-    ".kokoro/release/publish_javadoc11.cfg",
-    ".kokoro/release/publish_javadoc11.sh",
-    ".kokoro/release/snapshot.cfg",
-    ".kokoro/release/snapshot.sh",
-    ".kokoro/release/stage.cfg",
-    ".kokoro/release/stage.sh",
     ".kokoro/trampoline.sh",
     "CODE_OF_CONDUCT.md",
     "CONTRIBUTING.md",