Apply suggestions from code review

Author: marcalff

ext/include/opentelemetry/ext/http/client/curl/http_client_curl.h

@@ -358,7 +358,7 @@ class HttpClient : public opentelemetry::ext::http::client::HttpClient
   std::chrono::milliseconds scheduled_delay_milliseconds_;
 
   std::chrono::milliseconds background_thread_wait_for_;
-  std::atomic<bool> is_shutdown_;
+  std::atomic<bool> is_shutdown_{false};
 
   nostd::shared_ptr<HttpCurlGlobalInitializer> curl_global_initializer_;
 };

ext/test/http/curl_http_test.cc

@@ -548,9 +548,9 @@ TEST_F(BasicCurlHttpTests, ElegantQuitQuick)
   auto beg = std::chrono::system_clock::now();
   http_client->FinishAllSessions();
   http_client.reset();
-  // when use background_thread_wait_for_ should have no side effort on elegant quit
-  // it shoule less than scheduled_delay_milliseconds_
-  // because ci machine may slow, some take 10ms, so we assert it less than 20ms
+  // when background_thread_wait_for_ is used, it should have no side effect on elegant quit
+  // wait should be less than scheduled_delay_milliseconds_
+  // Due to load on CI hosts (some take 10ms), we assert it is less than 20ms
   auto cost = std::chrono::system_clock::now() - beg;
   ASSERT_TRUE(cost < std::chrono::milliseconds{20})
       << "cost ms: " << std::chrono::duration_cast<std::chrono::milliseconds>(cost).count()