Use elemental instead of cos

[frelon]

• Allow both cos.setup and elemental.setup in kernel cmdline.
• Use elemental.setup and elemental.disable in ISO grub config.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 72.56%. Comparing base (3028919) to head (f818565).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2014 +/- ## ======================================= Coverage 72.56% 72.56% ======================================= Files 76 76 Lines 8907 8907 ======================================= Hits 6463 6463 Misses 1910 1910 Partials 534 534 ```

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