feat: Add environment credentials feature tracking to User-Agent

- Add CREDENTIALS_ENV_VARS enum to UserAgentFeature with metric ID 'g'
- Track environment credentials usage in AWSClient::AttemptOneRequest
- Check for AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY presence
- Implements env-credentials SEP specification for business metrics
- Add unit test for environment credentials feature tracking

Resolves environment credentials tracking for User-Agent 2.1 business metrics.

Author: kai-ion

tests/aws-cpp-sdk-monitoring-unit-tests/CloudWatchUnitTest.cpp

@@ -46,35 +46,6 @@ class CloudWatchTest : public Aws::Testing::AwsCppSdkGTestSuite {
   }
 };
 
-class ClientHolder {
- public:
-  ClientHolder() : client(makeClient()) {
-    // init client again
-    client = makeClient();
-  }
-
-  PutMetricDataOutcome Foo() {
-    const auto response = client.PutMetricData(PutMetricDataRequest{});
-    return response;
-  }
-
-  const CloudWatchClient& getClient() { return client; }
-
-  CloudWatchClient&& moveClient() { return std::move(client); }
-
- private:
-  CloudWatchClient makeClient() {
-    Aws::Client::ClientConfigurationInitValues cfgInit;
-    cfgInit.shouldDisableIMDS = true;
-    Aws::Client::ClientConfiguration clientConfig(cfgInit);
-    clientConfig.region = Aws::Region::US_EAST_1;
-    AWSCredentials credentials{"mock", "credentials"};
-    return CloudWatchClient(credentials, clientConfig);
-  }
-
-  CloudWatchClient client;
-};
-
 TEST_F(CloudWatchTest, TestUserAgentCompressionTracking) {
 #if defined(ENABLED_ZLIB_REQUEST_COMPRESSION) && ENABLED_ZLIB_REQUEST_COMPRESSION == 1
   // Setup mock response with proper CloudWatch XML

tests/testing-resources/include/aws/testing/mocks/aws/client/MockAWSClient.h

@@ -54,20 +54,6 @@ class AmazonWebServiceRequestMock : public Aws::AmazonWebServiceRequest
         auto bodyString = ss.str();
         return bodyString.find("TestErrorInBodyOfResponse") != std::string::npos;
     }
-    
-    Aws::Client::CompressionAlgorithm GetSelectedCompressionAlgorithm(Aws::Client::RequestCompressionConfig config) const override {
-        if (config.useRequestCompression == Aws::Client::UseRequestCompression::ENABLE && m_body) {
-            m_body->seekg(0, m_body->end);
-            std::streampos pos = m_body->tellg();
-            m_body->seekg(0, m_body->beg);
-
-            if (pos != std::streampos(-1) && static_cast<size_t>(pos) >= config.requestMinCompressionSizeBytes) {
-              // todo does hit in dry run?
-                return Aws::Client::CompressionAlgorithm::GZIP;
-            }
-        }
-        return Aws::Client::CompressionAlgorithm::NONE;
-    }
 
 private:
     std::shared_ptr<Aws::IOStream> m_body;