twister: Fix bug re-running all tests when using test-only
twister: Fix bug re-running all tests when using test-only

When using both test-only and retry-failed flags, all tests would be
added to the test queue regardless if they failed or not. This commit
updates the logic to process test-only runs similar as other runs,
by adding tests to the queue with the 'run' operation directly.

Signed-off-by: Andreas Vibeto <e5b5c81871b266ee79ddfe5a473cc66a97fb9ca3@nordicsemi.no>

galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr