Remove Anvil machine configs and support

[Copilot]

Anvil at LCRC has been decommissioned, so mache now removes Anvil-specific support, configs, and documentation while keeping the upstream CIME machine config copy intact.

• Machine configuration cleanup: removed the Anvil machine config and spack templates; left config_machines.xml untouched.
• Runtime behavior: narrowed LCRC sync logic to Chrysalis only and updated the machine-info test to validate Chrysalis.
• Documentation updates: replaced Anvil references in user/developer guides and examples.

lcrc_machines = ['chrysalis']

Checklist

• User's Guide has been updated if needed
• Developer's Guide has been updated if needed
• Tests pass and new features are covered by tests
• PR description includes a summary and any relevant issue references

Original prompt

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This section details on the original issue you should resolve

<issue_title>Remove Anvil support</issue_title>
<issue_description>The machine Anvil at LCRC has been decommissioned. We need to remove it from mache and its documentation. The only place we should not remove it is from mache/cime_machine_config/config_machines.xml, since this is just a copy of a file maintained in the main E3SM repository. </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Remove Anvil support #347

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[xylar]

@copilot, please don't just remove Anvil from the documentation. Please also remove the machine config file and various spack support files specific to Anvil.

[xylar]

@copilot, once you have solidified your plan, please update the title of the PR to better reflect the scope of work.

[Copilot]

@copilot, please don't just remove Anvil from the documentation. Please also remove the machine config file and various spack support files specific to Anvil.

Removed the Anvil machine config and spack templates in commit 9279538.

[xylar]

This looks great! Thanks so much!