chore: update .kokoro/build.sh to run proxy when testing Cloud SQL samples (#1783)
chore: update .kokoro/build.sh to run proxy when testing Cloud SQL samples (#1783)

Co-authored-by: F. Hinkelmann <bfca2660d8321d14063d908366d26ce6f4981952@gmail.com>
GoogleCloudPlatform/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples