chore: set NODE_OPTIONS for increased memory limit (googleapis#3841)

* chore: set NODE_OPTIONS for increased memory limit

Increase Node.js memory limit for tests.

* Add '.kokoro/test.sh' to the ignored files list

* 🦉 Updates from OwlBot post-processor

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

* Increase Node.js memory limit in test script

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Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: sofisl

.kokoro/test.sh

@@ -22,6 +22,7 @@
   ".github/release-please.yml",
   '.kokoro/publish.sh',
   '.kokoro/release/publish.cfg',
+  '.kokoro/test.sh',
   '.github/workflows/ci.yaml',
   '.github/workflows/issues-no-repro.yaml'
 ])