Initramfs overwritten when testing new kernels

We have a config now that is used to create a file named `initramfs-linux.img` whenever a rebuild is triggered. This can be when deploying a new version or whenever a kernel is installed (Usually for testing purposes: https://github.com/ChimeraOS/chimeraos/issues/742#issuecomment-1694496633).

Our problem is that when you install a new kernel you'll end up with `initramfs-linux-chimeraos` or `initramfs-linux-mainline` which is what we want, but the `initramfs-linux` is overwritten based on the new kernel as well making it difficult to switch between the stock and test kernels. We want to keep the original initramfs for the stock kernel in place and not overwrite it based on the new one.

We need to stop renaming the name of the kernel and start handling it correctly in FRZR so that way we don't have unexpected issues like this arise. https://github.com/ChimeraOS/chimeraos/blob/f82f30f278494e0ac99841338548e2d90bf9f851/build-image.sh#L193