chore(rust): Rename is_numeric to is_primitive_numeric

[orlp]

It has lead to confusion in the past that Decimal is excluded from the is_numeric dtype method.

[codecov]

Codecov Report

Attention: Patch coverage is 94.33962% with 9 lines in your changes missing coverage. Please review.

Project coverage is 78.97%. Comparing base (04004b8) to head (e742541).
Report is 52 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-expr/src/reduce/mean.rs	0.00%	2 Missing ⚠️
...-core/src/chunked_array/builder/fixed_size_list.rs	0.00%	1 Missing ⚠️
...rates/polars-core/src/chunked_array/ops/reverse.rs	0.00%	1 Missing ⚠️
crates/polars-core/src/datatypes/any_value.rs	87.50%	1 Missing ⚠️
...tes/polars-core/src/series/implementations/list.rs	66.66%	1 Missing ⚠️
crates/polars-expr/src/reduce/var_std.rs	0.00%	1 Missing ⚠️
crates/polars-ops/src/series/ops/round.rs	75.00%	1 Missing ⚠️
...s-plan/src/plans/conversion/type_coercion/is_in.rs	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #20574      +/-   ##
==========================================
- Coverage   78.97%   78.97%   -0.01%     
==========================================
  Files        1564     1564              
  Lines      220807   220826      +19     
  Branches     2510     2510              
==========================================
+ Hits       174377   174390      +13     
- Misses      45855    45861       +6     
  Partials      575      575              

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