e2e: Ensure e2e.test is built with portable BLST

PR #1714 factored ANR installation into a common script, but in the
process removed the CGO configuration for BLST from tests.e2e.sh. The
result was sporadic e2e job failure whenever the github worker vm was
missing the instructions non-portable BLST required. Ensuring CGO is
explicitly configured for portable BLST in tests.e2e.sh should ensure
the e2e test binary can once again be built reliably.

Author: maru-ava

scripts/tests.e2e.sh

@@ -23,6 +23,13 @@ echo "installing avalanche-network-runner"
 ANR_WORKDIR="/tmp"
 ./scripts/install_anr.sh
 
+
+# Sourcing constants.sh ensures that the necessary CGO flags are set to
+# build the portable version of BLST. Without this, ginkgo may fail to
+# build the test binary if run on a host (e.g. github worker) that lacks
+# the instructions to build a non-portable BLST.
+source ./scripts/constants.sh
+
 #################################
 echo "building e2e.test"
 # to install the ginkgo binary (required for test build and run)