Show CUDA matmul precision info only ever once

[awaelchli]

What does this PR do?

Currently, whenever you call Fabric.setup() or Trainer.fit(), the info message

You are using a CUDA device ('NVIDIA A100-SXM4-40GB') that has Tensor Cores. To properly utilize them, you should set torch.set_float32_matmul_precision('medium' | 'high') which will trade-off precision for performance. For more details, read ...

is printed. Since this is a global setting for the entire script, I propose to only show the info once ever during the lifetime of the program. This avoids spamming the info message across the output.

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• Did you list all the breaking changes introduced by this pull request?
• Did you update the CHANGELOG? (not for typos, docs, test updates, or minor internal changes/refactors)

PR review

Anyone in the community is welcome to review the PR.
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cc @Borda @carmocca @justusschock @awaelchli

[github-actions]

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🟢 pytorch_lightning: Tests workflow

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fabric-cpu (ubuntu-20.04, lightning, 3.8, 1.11)	success	✅
fabric-cpu (ubuntu-20.04, lightning, 3.9, 1.12)	success	✅
fabric-cpu (ubuntu-20.04, lightning, 3.10, 1.13)	success	✅
fabric-cpu (ubuntu-20.04, lightning, 3.10, 2.0)	success	✅
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fabric-cpu (windows-2022, lightning, 3.8, 1.11)	success	✅
fabric-cpu (windows-2022, lightning, 3.9, 1.12)	success	✅
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fabric-cpu (windows-2022, lightning, 3.10, 2.0)	success	✅
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[codecov]

Codecov Report

Merging #17960 (536a78d) into master (199dc8f) will decrease coverage by 23%.
The diff coverage is 100%.

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #17960     +/-   ##
=========================================
- Coverage      84%      61%    -23%     
=========================================
  Files         425      420      -5     
  Lines       32053    31964     -89     
=========================================
- Hits        26816    19502   -7314     
- Misses       5237    12462   +7225