Use ConfigHelper.env() instead of System.getenv()

System.getenv() is forbidden by the project's forbiddenApis rules.
Replace with ConfigHelper.env() which is the approved way to read
environment variables. Add config-utils as compileOnly dependency.

Author: typotter

products/feature-flagging/feature-flagging-api/build.gradle.kts

@@ -44,6 +44,7 @@ dependencies {
   api("dev.openfeature:sdk:1.20.1")
 
   compileOnly(project(":products:feature-flagging:feature-flagging-bootstrap"))
+  compileOnly(project(":utils:config-utils"))
   compileOnly("io.opentelemetry:opentelemetry-api:1.47.0")
   compileOnly("io.opentelemetry:opentelemetry-sdk-metrics:1.47.0")
   compileOnly("io.opentelemetry:opentelemetry-exporter-otlp:1.47.0")

products/feature-flagging/feature-flagging-api/src/main/java/datadog/trace/api/openfeature/FlagEvalMetrics.java

@@ -1,5 +1,6 @@
 package datadog.trace.api.openfeature;
 
+import datadog.trace.config.inversion.ConfigHelper;
 import dev.openfeature.sdk.ErrorCode;
 import io.opentelemetry.api.common.AttributeKey;
 import io.opentelemetry.api.common.Attributes;
@@ -43,9 +44,9 @@ class FlagEvalMetrics implements Closeable {
 
   FlagEvalMetrics() {
     try {
-      String endpoint = System.getenv(ENDPOINT_ENV);
+      String endpoint = ConfigHelper.env(ENDPOINT_ENV);
       if (endpoint == null || endpoint.isEmpty()) {
-        String base = System.getenv(ENDPOINT_GENERIC_ENV);
+        String base = ConfigHelper.env(ENDPOINT_GENERIC_ENV);
         if (base != null && !base.isEmpty()) {
           endpoint = base.endsWith("/") ? base + "v1/metrics" : base + "/v1/metrics";
         } else {