Chore: Add env var check to `make drone` (#83337)

Makefile

@@ -318,6 +318,7 @@ gen-ts:
 # Use this make target to regenerate the configuration YAML files when
 # you modify starlark files.
 drone: $(DRONE)
+	bash scripts/drone/env-var-check.sh
 	$(DRONE) starlark --format
 	$(DRONE) lint .drone.yml --trusted
 	$(DRONE) --server https://drone.grafana.net sign --save grafana/grafana

scripts/drone/env-var-check.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+# ensure DRONE_SERVER and DRONE_TOKEN env variables are set
+if [ -z "$DRONE_SERVER" ]; then
+    echo "DRONE_SERVER environment variable is not set."
+    exit 1
+fi
+
+if [ -z "$DRONE_TOKEN" ]; then
+    echo "DRONE_TOKEN environment variable is not set."
+    exit 1
+fi