chore: stop auditing installed packages every time (aws#6790)

Audit checks are increasing the chance of '503 Service Unavailable'
during builds. Stop auditing so we have lower build failures.

Github already provides this security audit and can be found at
https://github.com/aws/aws-cdk/network/alerts

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

.yarnrc

@@ -1,2 +1 @@
 --install.check-files     true      # install will verify file tree of packages for consistency
---install.audit           true      # Run vulnerability audit on installed packages