Removed errornous kernel parameters overwrite to fix CentOS 6.6 install

[hpaluch-pil]

Fixes Issue #3341 caused by db64d32

The kernel_params key should be removed from .cfg - not erased.

After applying this fix, CentOS 6.6. unattened install should work again, for example:

avocado run \
   --vt-guest-os Guest.Linux.CentOS.6.6.x86_64 \
   unattended_install.cdrom.extra_cdrom_ks.default_install.aio_threads

[luckyh]

Hi @hpaluch-pil the code looks good to me, would you please check the CI failure and fix it? thanks!

[hpaluch-pil]

OK - I signed that commit - it should resolve that "signed-of-by" failure.

[hpaluch-pil]

I'm unable to see why it failed now: https://github.com/avocado-framework/avocado-vt/runs/5228939021?check_suite_focus=true

[luckyh]

I'm unable to see why it failed now: https://github.com/avocado-framework/avocado-vt/runs/5228939021?check_suite_focus=true

@hpaluch-pil I just did a quick check on the last commit (9e891cb) message [1] and it seems the signature was still missing. As your can see from the example below [2] there is a Signed-off-by line under the subject. Please help double confirm that, thanks!

[1] https://patch-diff.githubusercontent.com/raw/avocado-framework/avocado-vt/pull/3342.patch
[2] https://patch-diff.githubusercontent.com/raw/avocado-framework/avocado-vt/pull/3354.patch

[hpaluch-pil]

Finally got commit signing right (I hope) using git commit --gpg-sign=KEY_ID -S --amend instead of just git commit -s --amend