fix(tests): add 10ms delay after we are done with stubr

[argl]

• Make sure we drop any stubr instance deliberately, both with the attribute macro and with manual setup.
• Drop stubr using our own async helper function drop_stubr(stubr: Stubr)that drops it and adds 10ms of delay.
• Remove all older check/wait/sleep functions around stubr.
• Make sure we only use a single instance of stubr inside a test by splitting tests up.

I ran the tests in a loop on my local machine, this version did not fail after around 130 invocations which is where I stopped it.

Shell script to run tests it in a loop:

LOGFILE=testlog.log
export RUST_LOG=rumba:info
export MDN_SETTINGS=.settings.test.toml
echo "$(date -Iseconds) START" >$LOGFILE
while true; do
	cargo test --all -- --test-threads=1 --nocapture; 
	if [ $? -ne 0 ]; then 
		echo "$(date -Iseconds) ===== The test failed. ======" | tee -a $LOGFILE; 
		break; 
	else 
		echo "$(date -Iseconds) OK" >>$LOGFILE
		sleep 0.1; 
		clear; 
	fi; 
done

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[fiji-flo]

Thanks looks good. And thanks for changing the sleep 👍

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