Revert "[arm] Refactor installer and build to allow arm builds targeted at grub platforms"

[qiluo-msft]

Reverts #11341

Why I did it

1. The original PR has some issues [arm] Refactor installer and build to allow arm builds targeted at grub platforms #11341 (comment)

2. The %%EXTRA_CMDLINE_LINUX%% is not replaced to the real value, it has impact on the kernel parameter settings.
   See the log sonic-vs.img.gz.log in the latest master build. In the grub.cfg, the %%EXTRA_CMDLINE_LINUX%% is set in the linux command line.

Installing for i386-pc platform.
Installation finished. No error reported.
Switch CPU vendor is: GenuineIntel
Switch CPU cstates are: disabled
EXTRA_CMDLINE_LINUX=%%EXTRA_CMDLINE_LINUX%%
Installed SONiC base image SONiC-OS successfully
ONIE: NOS install successful: file://dev/vdb/onie-installer.bin

[qiluo-msft]

@alexrallen Please help check. You may redo your original PR after this revert.

[alexrallen]

What is the reasoning of this revert? The PR description fails to justify such a measure.

1. I don't see how a revert is justified by non-functional code organization issues. While I would have preferred any issues with the file extensions / organization to be reported with the original PR I do not see how this could not be resolved by an additional PR on top of what already exists.

2. Your second point refers to an issue that I am under the impression that is being resolved by another PR (#11572) What additional issues exist that warrant a revert?

[qiluo-msft]

Close this in favor of #11572