revert signer StableRef changes

Author: lauzadis

aws-crt-kotlin/native/src/aws/sdk/kotlin/crt/auth/signing/AwsSignerNative.kt

@@ -37,6 +37,7 @@ public actual object AwsSigner {
         request.toNativeRequest().usePinned { nativeRequest ->
             // Pair of HTTP request and callback channel containing the signature
             val userData = nativeRequest to Channel<ByteArray>(1)
+            val userDataStableRef = StableRef.create(userData)
 
             val signable = checkNotNull(
                 aws_signable_new_http_request(
@@ -47,20 +48,21 @@ public actual object AwsSigner {
 
             val nativeSigningConfig: CPointer<aws_signing_config_base> = config.toNativeSigningConfig().reinterpret()
 
-            StableRef.create(userData).use { userDataStableRef ->
-                awsAssertOpSuccess(
-                    aws_sign_request_aws(
-                        allocator = Allocator.Default.allocator,
-                        signable = signable,
-                        base_config = nativeSigningConfig,
-                        on_complete = staticCFunction(::signCallback),
-                        userdata = userDataStableRef.asCPointer(),
-                    ),
-                ) { "sign() aws_sign_request_aws" }
+            awsAssertOpSuccess(
+                aws_sign_request_aws(
+                    allocator = Allocator.Default.allocator,
+                    signable = signable,
+                    base_config = nativeSigningConfig,
+                    on_complete = staticCFunction(::signCallback),
+                    userdata = userDataStableRef.asCPointer(),
+                ),
+            ) { "sign() aws_sign_request_aws" }
 
-                val callbackChannel = userDataStableRef.get().second
-                val signature = callbackChannel.receive() // wait for async signing to complete....
-                return AwsSigningResult(nativeRequest.get().toHttpRequest(), signature)
+            val callbackChannel = userDataStableRef.get().second
+            val signature = callbackChannel.receive() // wait for async signing to complete....
+            return AwsSigningResult(nativeRequest.get().toHttpRequest(), signature).also {
+                userDataStableRef.dispose()
+                callbackChannel.close()
             }
         }
     }