Use 32bit floats for surfaces

[dafeda]

Issue
Resolves #6059

Pre review checklist

• Read through the code changes carefully after finishing work
• Make sure tests pass locally (after every commit!)
• Prepare changes in small commits for more convenient review (optional)
• PR title captures the intent of the changes, and is fitting for release notes.
• Updated documentation
• Ensured that unit tests are added for all new behavior (See
  Ground Rules),
  and changes to existing code have good test coverage.

Pre merge checklist

• Added appropriate release note label
• Commit history is consistent and clean, in line with the contribution guidelines.

[codecov-commenter]

Codecov Report

Merging #6106 (8f2c3bd) into main (61ec478) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #6106   +/-   ##
=======================================
  Coverage   82.49%   82.49%           
=======================================
  Files         350      350           
  Lines       21486    21488    +2     
  Branches      826      826           
=======================================
+ Hits        17725    17727    +2     
  Misses       3467     3467           
  Partials      294      294           

Files Changed	Coverage Δ
src/ert/storage/migration/block_fs.py	97.89% <ø> (ø)
src/ert/config/surface_config.py	100.00% <100.00%> (ø)
src/ert/storage/local_experiment.py	95.45% <100.00%> (+0.06%)	⬆️

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