remove ppc from arch migrator

[minrk]

Description:

removes ppc from the aarch migrator, so we don't keep getting new ppc builds without explicit user requests.

I'm not sure if there's more to do here, or if the name change would cause a problem.

Checklist:

• Pydantic model updated or no update needed

Cross-refs, links to issues, etc:

In conda-forge/conda-forge.github.io#2510 (comment) it was proposed to split the ppc migrator, but I think it is more likely that ppc builds will stop altogether (I'm currently drafting an RFC to propose just that)

RFC for dropping ppc: conda-forge/conda-forge.github.io#2781

[beckermr]

We need to be very careful with renaming the migrator since it could cause the bot to go and remake all of the aarch PRs.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 80.64%. Comparing base (698ec83) to head (c440a7a).
⚠️ Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
conda_forge_tick/migrators/arch.py	0.00%	1 Missing ⚠️

❌ Your patch check has failed because the patch coverage (0.00%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5862   +/-   ##
=======================================
  Coverage   80.64%   80.64%           
=======================================
  Files         146      146           
  Lines       17393    17393           
=======================================
  Hits        14027    14027           
  Misses       3366     3366           

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[isuruf]

Can you change pr_title to be something like `Linux aarch64 Migrator

[minrk]

@isuruf makes sense, done.