chore: fix nightly samples check (#1976)

* chore: fix nighly samples check

* chore:  test if teh new setup works

* chore: add regular presubmit samples check

Author: Neenu1995

.kokoro/continuous/java11-samples.cfg

@@ -29,5 +29,5 @@ env_vars: {
 
 env_vars: {
   key: "SECRET_MANAGER_KEYS"
-  value: "java-docs-samples-service-account"
+  value: "java-docs-samples-service-account, java-bigquery-samples-secrets"
 }

.kokoro/continuous/java8-samples.cfg

@@ -30,6 +30,10 @@ source ${scriptDir}/common.sh
 
 # Setup required env variables
 source ${KOKORO_GFILE_DIR}/secret_manager/java-bigquery-samples-secrets
+# if GOOGLE_APPLICATION_CREDENTIALS is specified as a relative path, prepend Kokoro root directory onto it
+if [[ ! -z "${GOOGLE_APPLICATION_CREDENTIALS}" && "${GOOGLE_APPLICATION_CREDENTIALS}" != /* ]]; then
+    export GOOGLE_APPLICATION_CREDENTIALS=$(realpath ${KOKORO_GFILE_DIR}/${GOOGLE_APPLICATION_CREDENTIALS})
+fi
 echo "********** Successfully Set All Environment Variables **********"
 
 # Move into the samples directory

.kokoro/nightly/java11-samples.cfg

@@ -17,14 +17,9 @@
 import synthtool.languages.java as java
 
 java.common_templates(excludes=[
-    '.kokoro/continuous/java8-samples.cfg',
-    '.kokoro/continuous/java11-samples.cfg',
-    '.kokoro/nightly/java8-samples.cfg',
-    '.kokoro/nightly/java11-samples.cfg',
     '.kokoro/nightly/samples.cfg',
-    '.kokoro/presubmit/java8-samples.cfg',
-    '.kokoro/presubmit/java11-samples.cfg',
+    '.kokoro/presubmit/samples.cfg',
     '.kokoro/dependencies.sh',
     'codecov.yaml',
     'renovate.json',
-])
+])