message: Fix memory leak when resetting the cache
  Summary: Fix T40226
  Test Plan: CI, in-memory cache showing executables being de-allocated.
  Reviewers: babakk, jakeh, #tensorflow, simonl, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, vladimirm
  Maniphest Tasks: T40226
diff: @@ -46,7 +46,10 @@ Status DeleteXlaCompilationCache(XlaDevice* device) {
  Status lookup_status = resource_manager->Lookup(
  resource_manager->default_container(), "xla_cache", &cache);
  const bool has_cache = lookup_status.ok() && cache;
  +
  if (has_cache) {
  + // Remove the extra reference acquired during the lookup.
  + cache->Unref();
  // Fragile but the arguments to Delete correspond to the values used when
  // constructing the cache in CompileToLocalExecutable (kernels/xla_ops.cc).
  // It'll be lazily recreated if the device is used for compilation again.
  