[8.x] Fix option overrides

[driesvints]

This PR fixes an issue with option overriding introduced in #40954. The problem is that by default a value of 'options' => null gets added when the default value of a HTTP call (get, post,...) is left empty. Because array_merge_recursive was changed to array_replace_recursive, the default value removed the value of query set with withOptions.

The way I fixed it is to filter out any null value of options before sending the request. It doesn't seems you want to add null values to a request? However, if users are explicitly removing options set with withOptions by assigning null values, this will no longer work. But all tests pass right now and the docs don't note anything about that behavior so I don't think that's expected.

Related: #40954 & 30e341b

Fixes #41382

[taylorotwell]

Fixed a54f481

[taylorotwell]

Fixed a54f481