Fix networkinterface non-blocking status test

[jarvte]

Description

Fix was to add some time between iterations connect-disconnect. In cellular disconnect, cellular network may send disconnect events and if those events come when connect is already ongoing test will fail.
So wait a bit after disconnect so that disconnect events should be over.

Pull request type

[ ] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Docs update
[x] Test update
[ ] Breaking change

Reviewers

@AriParkkila

Release Notes

[ciarmcom]

@jarvte, thank you for your changes.
@AriParkkila @ARMmbed/mbed-os-test @ARMmbed/mbed-os-ipcore @ARMmbed/mbed-os-maintainers please review.

[michalpasztamobica]

I don't fully understand why would extra disconnect messages be sent to callback if the socket has already been disconnected? Maybe it is better to prevent them being sent? The test seems to be well tailored...

In case there is a good reason to keep sending messages to callback after socket got disconnected... Do we know how many messages are expected? Perhaps we can consciously receive them, to make sure nothing will spuriously break the subsequent connect()?

Is only this one particular test affected or do other tests also need to wait for pending messages to arrive?

[SeppoTakalo]

I don't fully understand why would extra disconnect messages be sent to callback if the socket has already been disconnected?

Not socket.. this is for NetworkInterface.

And in theory, you cannot destroy interface, but you can destroy socket.
Therefore disconnected interface may still keep posting events. Some are generic "disconnected" some may be cellular specific.

[jarvte]

Force-pushed astyle fixes

[0xc0170]

CI started

[mbed-ci]

Test run: SUCCESS

Summary: 4 of 4 test jobs passed
Build number : 1
Build artifacts