fix: do not use EnvironmentExist in GetEnvironmentValue (#83)

EnvironmentExist should not be used because it checks for DD_ prefixed
keys most of the time, however GetEnvironmentValue has some extra logic
for PYROSCOPE_ prefixed keys

Author: korniltsev

profiler/src/ProfilerEngine/Datadog.Profiler.Native/Configuration.cpp

@@ -682,7 +682,8 @@ static bool convert_to(shared::WSTRING const& s, DeploymentMode& result)
 template <typename T>
 T Configuration::GetEnvironmentValue(shared::WSTRING const& name, T const& defaultValue)
 {
-    if (!shared::EnvironmentExist(name)) return defaultValue;
+    // pyroscope: next line is removed because shared::GetEnvironmentValue has DD_ => PYROSCOPE_ fallback
+    // if (!shared::EnvironmentExist(name)) return defaultValue;
 
     T result{};
     auto r = shared::GetEnvironmentValue(name);