docs(releasenotes): note opt-in native heap gotter wheel build

Document setup.py gate: gotter cdylib ships only when
DD_PROFILING_NATIVE_HEAP_ENABLED=1 at build time; musl always skips.

Author: vlad-scherbich

releasenotes/notes/native-heap-gotter-opt-in-wheel-build-8f3a2c1d9e4b5a07.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    profiling: ``libdd_heap_gotter`` is now included in Linux wheels only when the
+    wheel is built with ``DD_PROFILING_NATIVE_HEAP_ENABLED=1``. Default packaging
+    builds omit the cdylib. Musllinux and Alpine sdist builds always skip the
+    gotter cargo build even when that env var is set.