🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Author: gcf-owl-bot[bot]

.kokoro/build.sh

@@ -15,13 +15,11 @@
 
 set -eo pipefail
 
-CURRENT_DIR=$(dirname "${BASH_SOURCE[0]}")
-
 if [[ -z "${PROJECT_ROOT:-}" ]]; then
-  PROJECT_ROOT=$(realpath "${CURRENT_DIR}/..")
+    PROJECT_ROOT="github/python-bigquery"
 fi
 
-pushd "${PROJECT_ROOT}"
+cd "${PROJECT_ROOT}"
 
 # Disable buffering, so that the logs stream through.
 export PYTHONUNBUFFERED=1
@@ -30,16 +28,10 @@ export PYTHONUNBUFFERED=1
 env | grep KOKORO
 
 # Setup service account credentials.
-if [[ -f "${KOKORO_GFILE_DIR}/service-account.json" ]]
-then
-  export GOOGLE_APPLICATION_CREDENTIALS=${KOKORO_GFILE_DIR}/service-account.json
-fi
+export GOOGLE_APPLICATION_CREDENTIALS=${KOKORO_GFILE_DIR}/service-account.json
 
 # Setup project id.
-if [[ -f "${KOKORO_GFILE_DIR}/project-id.json" ]]
-then
-  export PROJECT_ID=$(cat "${KOKORO_GFILE_DIR}/project-id.json")
-fi
+export PROJECT_ID=$(cat "${KOKORO_GFILE_DIR}/project-id.json")
 
 # If this is a continuous build, send the test log to the FlakyBot.
 # See https://github.com/googleapis/repo-automation-bots/tree/main/packages/flakybot.
@@ -54,7 +46,7 @@ fi
 # If NOX_SESSION is set, it only runs the specified session,
 # otherwise run all the sessions.
 if [[ -n "${NOX_SESSION:-}" ]]; then
-  python3 -m nox -s ${NOX_SESSION:-}
+    python3 -m nox -s ${NOX_SESSION:-}
 else
-  python3 -m nox
+    python3 -m nox
 fi