chore: removes unused kokoro config files (#110)

* cleanup: removes unused kokoro config files

Removes unused kokoro files from the java library template. We have
stopped running some of these due to Github quota issues.

* fix:reverts back samples.cfg files

The files presubmit/samples.cfg and nightly/samples.cfg should remain in
the java template repository.

Co-authored-by: Jeffrey Rennie <rennie@google.com>

Source-Author: Thiago Nunes <thiagotnunes@gmail.com>
Source-Date: Thu Aug 6 09:48:58 2020 +1000
Source-Repo: googleapis/synthtool
Source-Sha: 4530cc6ff080ef8aca258c1ec92c4db10a1bbfb4
Source-Link: googleapis/synthtool@4530cc6

synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-shared-dependencies.git",
-        "sha": "825f29c8b310ae7eb0e8d695ed240dbaabc5041c"
+        "sha": "d0d16a1c3e0dc99176f6555ad648ea8b74b6fdcf"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "dd230c816f88d0141fcd0be83498986287220d1b"
+        "sha": "4530cc6ff080ef8aca258c1ec92c4db10a1bbfb4"
       }
     }
   ],
@@ -30,27 +30,16 @@
     ".kokoro/common.cfg",
     ".kokoro/common.sh",
     ".kokoro/continuous/common.cfg",
-    ".kokoro/continuous/dependencies.cfg",
-    ".kokoro/continuous/integration.cfg",
-    ".kokoro/continuous/java11.cfg",
-    ".kokoro/continuous/java7.cfg",
-    ".kokoro/continuous/java8-osx.cfg",
-    ".kokoro/continuous/java8-win.cfg",
     ".kokoro/continuous/java8.cfg",
-    ".kokoro/continuous/lint.cfg",
-    ".kokoro/continuous/propose_release.cfg",
-    ".kokoro/continuous/samples.cfg",
     ".kokoro/dependencies.sh",
     ".kokoro/linkage-monitor.sh",
     ".kokoro/nightly/common.cfg",
-    ".kokoro/nightly/dependencies.cfg",
     ".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/nightly/lint.cfg",
     ".kokoro/nightly/samples.cfg",
     ".kokoro/populate-secrets.sh",
     ".kokoro/presubmit/clirr.cfg",