chore: (fix) jsii-pacmak patch not applied during packing (#16877)

The pack on v2 is currently broken due to a bug in jsii-pacmak <= 1.38.0 that
packs all modules in parallel, regardless of dependencies between the
modules. That breaks on building the alpha modules, since they rely on
aws-cdk-lib, but often end up being packed first. A fix was created in jsii
(aws/jsii#3045), but to unblock the build earlier, a
patch was created to apply the fix within the CDK prior to the next jsii release
(#16871).  Unfortunately, our build
"transform" step runs a `lerna` command that re-installs jsii-pacmak, removing
the patch. Calling `yarn install` here again to re-install and re-apply the
patch prior to packing.

_Note: This will become obsolete once jsii-pacmak 1.39.0 is released_

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

pack.sh

@@ -7,6 +7,18 @@ export PATH=$PWD/node_modules/.bin:$PATH
 export NODE_OPTIONS="--max-old-space-size=8192 ${NODE_OPTIONS:-}"
 root=$PWD
 
+### HACKS - Remove once jsii-pacmak@>=1.39.0
+# Temporary work-around
+# The pack on v2 is currently broken due to a bug in jsii-pacmak <= 1.38.0 that packs all modules in
+# parallel, regardless of dependencies between the modules. That breaks on building the alpha modules,
+# since they rely on aws-cdk-lib, but often end up being packed first. A fix was created in jsii
+# (https://github.com/aws/jsii/pull/3045), but to unblock the build earlier, a patch was created to
+# apply the fix within the CDK prior to the next jsii release (https://github.com/aws/aws-cdk/pull/16871).
+# Unfortunately, our build "transform" step runs a `lerna` command that re-installs jsii-pacmak, removing
+# the patch. Calling `yarn install` here again to re-install and re-apply the patch prior to packing.
+yarn install --frozen-lockfile
+### HACKS - Remove once jsii-pacmak@>=1.39.0
+
 # Get version and changelog file name (these require that .versionrc.json would have been generated)
 version=$(node -p "require('./scripts/resolve-version').version")
 changelog_file=$(node -p "require('./scripts/resolve-version').changelogFile")