perf: optimized imports and initializations

[sbrunato]

Optimize imports and initializations for better perf

[github-actions]

Benchmark comparison

Compared baseline: origin/develop
Compared candidate: 1af53d6

--------------------------------- benchmark: 5 tests, 2 sources ---------------------------------
Name (time in us)                                     baseline Median  candidate Median   ΔMedian
-------------------------------------------------------------------------------------------------
test_benchmark_eoproduct_instantiation                        32.8825           30.7590     -6.5%
test_benchmark_eoproduct_assets_population                    63.1240           60.6740     -3.9%
test_benchmark_import_eodag_cube_subprocess               16,483.5105       16,005.3090     -2.9%
test_benchmark_to_xarray_local                            23,581.0550       23,799.9820     +0.9%
test_benchmark_import_eodag_public_api_subprocess      1,401,617.0805      939,095.1875    -33.0%
-------------------------------------------------------------------------------------------------

Legend:
  Cyan: reference source for comparison. Green: improvement, Red: regression.
  Δ: percentage change from reference source.