feat: skip all migrators on schema v1 for now

[beckermr]

This PR skips all migrators on the v1 schema for now.

closes #2918

[wolfv]

Thanks, looks good!

[codecov]

Codecov Report

Attention: Patch coverage is 79.66102% with 12 lines in your changes missing coverage. Please review.

Project coverage is 76.29%. Comparing base (3001670) to head (799f214).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
conda_forge_tick/feedstock_parser.py	25.00%	6 Missing ⚠️
conda_forge_tick/migrators/core.py	72.72%	3 Missing ⚠️
conda_forge_tick/migrators/cross_compile.py	90.00%	1 Missing ⚠️
conda_forge_tick/migrators/jinja2_vars_cleanup.py	50.00%	1 Missing ⚠️
conda_forge_tick/migrators/numpy2.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3006      +/-   ##
==========================================
+ Coverage   76.28%   76.29%   +0.01%     
==========================================
  Files         115      115              
  Lines       12532    12550      +18     
==========================================
+ Hits         9560     9575      +15     
- Misses       2972     2975       +3     

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