[8.x] Do not execute beforeSending callbacks twice

[rodrigopedra]

As #37105 outlines, the HTTP client executes the beforeSending callbacks twice when sending a request.

This is due to both buildBeforeSendingHandler and buildRecordHandler running the runBeforeSendingCallbacks method, and both this build* methods being added to the request middleware stack.

framework/src/Illuminate/Http/Client/PendingRequest.php

Lines 786 to 797 in 5a65f25

	public function buildHandlerStack()
	{
	return tap(HandlerStack::create(), function ($stack) {
	$stack->push($this->buildBeforeSendingHandler());
	$stack->push($this->buildRecorderHandler());
	$stack->push($this->buildStubHandler());
	$this->middleware->each(function ($middleware) use ($stack) {
	$stack->push($middleware);
	});
	});
	}

framework/src/Illuminate/Http/Client/PendingRequest.php

Lines 804 to 811 in 5a65f25

	public function buildBeforeSendingHandler()
	{
	return function ($handler) {
	return function ($request, $options) use ($handler) {
	return $handler($this->runBeforeSendingCallbacks($request, $options), $options);
	};
	};
	}

framework/src/Illuminate/Http/Client/PendingRequest.php

Lines 818 to 834 in 5a65f25

	public function buildRecorderHandler()
	{
	return function ($handler) {
	return function ($request, $options) use ($handler) {
	$promise = $handler($this->runBeforeSendingCallbacks($request, $options), $options);
	return $promise->then(function ($response) use ($request, $options) {
	optional($this->factory)->recordRequestResponsePair(
	(new Request($request))->withData($options['laravel_data']),
	new Response($response)
	);
	return $response;
	});
	};
	};
	}

This PR removes the redundant call from buildRecordHandler (as it is ran after buildBeforeSendingHandler in the middleware stack) and simply calling $promise = $handler($request, $options); to keep it as a "after" middleware, using the example in Guzzle docs:

https://docs.guzzlephp.org/en/stable/handlers-and-middleware.html#middleware

Closes #37105

[taylorotwell]

Thank you