use string constant instead of string

Author: lbloder

sentry-android-core/src/main/java/io/sentry/android/core/AndroidContinuousProfiler.java

@@ -301,7 +301,7 @@ private void stop(final boolean restartProfiler) {
                   endData.measurementsMap,
                   endData.traceFile,
                   startProfileChunkTimestamp,
-                  "android"));
+                  ProfileChunk.PLATFORM_ANDROID));
         }
       }