Fix params setting

[YamLyubov]

Setting of 'nested_space' parameters for node while tuning was not working correctly. While tuning new parameters were at first set for OptGraph and then OptGraph was restored to Pipeline. While restoring, pipeline nodes were created from scratch and new parameters were passed through the constructor of the Node class. That is why 'nested_space' parameters were not processed as they should.

Also examples/simple/multitask_classification_regression_api.py was removed as the functionality is no longer supported.

[aim-pep8-bot]

Hello @YamLyubov! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers:

Comment last updated at 2023-07-28 11:11:25 UTC

[codecov[bot]]

Codecov Report

Merging #1121 (8c053df) into master (07edf3e) will increase coverage by 0.02%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1121      +/-   ##
==========================================
+ Coverage   78.54%   78.57%   +0.02%     
==========================================
  Files         131      131              
  Lines        9323     9321       -2     
==========================================
+ Hits         7323     7324       +1     
+ Misses       2000     1997       -3     

Files Changed	Coverage Δ
fedot/core/pipelines/node.py	94.88% <100.00%> (+1.62%)	:arrow_up:
fedot/core/utils.py	54.79% <100.00%> (+0.62%)	:arrow_up:

... and 3 files with indirect coverage changes