twister: Convert platform names before printing

[gchwier]

Just move a code with workaround to convert platform names to the full name with variants.
It fixes an issue, that not every platforms are printed before running tests.

Before fix:
(when using a platform that has a variant, but not given it with --platform or in hardware map):
$ZEPHYR_BASE/scripts/twister -v -T samples/hello_world -p nrf9160dk/nrf9160 --device-testing --device-serial /dev/ttyACM0

INFO    - Building initial testsuite list...
Device testing on:
| Platform   | ID   | Serial device   |
|------------|------|-----------------|
...
INFO    - 1/1 [email protected]/nrf9160  samples/hello_world/sample.basic.helloworld        PASSED (device 1.609s <zephyr>)
...
INFO    - 1 test configurations executed on platforms, 0 test configurations were only built.
Hardware distribution summary:
| Board                    | ID   |   Counter |   Failures |
|--------------------------|------|-----------|------------|
| [email protected]/nrf9160 |      |         1 |          0 |

after fix, you can find platform also in initial list:

INFO    - Building initial testsuite list...
Device testing on:
| Platform                 | ID   | Serial device   |
|--------------------------|------|-----------------|
| [email protected]/nrf9160 |      | /dev/ttyACM0    |

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud