Backport of Shuffle CICD tests to spread worker load. into release/1.…

…15.x (#19518)

backport of commit b8a18c4

Co-authored-by: Derek Menteer <derek.menteer@hashicorp.com>

.github/scripts/set_test_package_matrix.sh

@@ -3,6 +3,6 @@ set -euo pipefail
 export RUNNER_COUNT=$1
 
 # set matrix var to list of unique packages containing tests
-matrix="$(go list -json="ImportPath,TestGoFiles" ./... | jq --compact-output '. | select(.TestGoFiles != null) | .ImportPath' | jq --slurp --compact-output '.' | jq --argjson runnercount $RUNNER_COUNT  -cM '[_nwise(length / $runnercount | floor)]'))"
+matrix="$(go list -json="ImportPath,TestGoFiles" ./... | jq --compact-output '. | select(.TestGoFiles != null) | .ImportPath' | shuf | jq --slurp --compact-output '.' | jq --argjson runnercount $RUNNER_COUNT  -cM '[_nwise(length / $runnercount | floor)]'))"
 
 echo "matrix=${matrix}" >> "${GITHUB_OUTPUT}"