Remove qemu and switch to skipemulation plan

[am11]

No description provided.

[am11]

@akoeplinger, looks like we need x64 keys:

 > [builder 2/4] RUN rootfsEnv="/usr/local/share/rootfs" &&     python3 -m venv "$rootfsEnv" &&     "$rootfsEnv/bin/python" -m pip install aiohttp zstandard &&     PYTHON_EXECUTABLE="$rootfsEnv/bin/python" /scripts/eng/common/cross/build-rootfs.sh x64 xenial --skipunmount --skipemulation:
10.81 Exception: Signature verification failed: gpg: Signature made Thu May 14 21:17:04 2026 UTC
10.81 gpg:                using DSA key 630239CC130E1A7FD81A27B140976EAF437D05B5
10.81 gpg: Can't check signature: No public key
10.81 gpg: Signature made Thu May 14 21:17:04 2026 UTC
10.81 gpg:                using RSA key 790BC7277767219C42C86F933B4FE6ACC0B21F32
10.81 gpg: Good signature from "Ubuntu Archive Automatic Signing Key (2012) <ftpmaster@ubuntu.com>" [unknown]
10.81 gpg: WARNING: This key is not certified with a trusted signature!
10.81 gpg:          There is no indication that the signature belongs to the owner.
10.81 Primary key fingerprint: 790B C727 7767 219C 42C8  6F93 3B4F E6AC C0B2 1F32
10.81 
------
Dockerfile:6
--------------------
   5 |     
   6 | >>> RUN rootfsEnv="/usr/local/share/rootfs" && \
   7 | >>>     python3 -m venv "$rootfsEnv" && \
   8 | >>>     "$rootfsEnv/bin/python" -m pip install aiohttp zstandard && \
   9 | >>>     PYTHON_EXECUTABLE="$rootfsEnv/bin/python" /scripts/eng/common/cross/build-rootfs.sh x64 xenial --skipunmount --skipemulation
  10 |     
---------------

[am11]

Passed with dotnet/arcade#16823 changes. I'll revert clone change here once arcade PR is merged.

[am11]

Suggested change

	# git clone --depth 1 --single-branch https://github.com/dotnet/arcade /scripts
	git clone --depth 1 --single-branch https://github.com/am11/arcade --single-branch --depth 1 --branch patch-19 /scripts
	git clone --depth 1 --single-branch https://github.com/dotnet/arcade /scripts

[am11]

Suggested change

	# git clone --depth 1 --single-branch https://github.com/dotnet/arcade /scripts
	git clone --depth 1 --single-branch https://github.com/am11/arcade --single-branch --depth 1 --branch patch-19 /scripts
	git clone --depth 1 --single-branch https://github.com/dotnet/arcade /scripts

[am11]

Suggested change

	# git clone --depth 1 --single-branch https://github.com/dotnet/arcade /scripts
	git clone --depth 1 --single-branch https://github.com/am11/arcade --single-branch --depth 1 --branch patch-19 /scripts
	git clone --depth 1 --single-branch https://github.com/dotnet/arcade /scripts

[am11]

Suggested change

	# git clone --depth 1 --single-branch https://github.com/dotnet/arcade /scripts
	git clone --depth 1 --single-branch https://github.com/am11/arcade --single-branch --depth 1 --branch patch-19 /scripts
	git clone --depth 1 --single-branch https://github.com/dotnet/arcade /scripts