[ntuple] Change `FromRNTuple` to regular RDF constructor in tutorials

[enirolf]

• [x] tested changes locally
• [x] updated the docs (if necessary)

[phsft-bot]

Starting build on ROOT-performance-centos8-multicore/soversion, ROOT-ubuntu2204/nortcxxmod, ROOT-ubuntu2004/python3, mac12arm/cxx20, windows10/default How to customize builds

[phsft-bot]

Build failed on ROOT-ubuntu2204/nortcxxmod. Running on root-ubuntu-2204-2.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build See console output.

Failing tests:

• projectroot.tmva.pymva.test.PyMVA_Torch_Regression
• projectroot.tmva.pymva.test.PyMVA_Torch_Classification
• projectroot.tmva.pymva.test.PyMVA_Torch_Multiclass
• projectroot.tmva.pymva.test.gtest_tmva_pymva_test_TestRModelParserPyTorch

[phsft-bot]

Build failed on ROOT-ubuntu2004/python3. Running on root-ubuntu-2004-1.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build See console output.

Failing tests:

• projectroot.tmva.pymva.test.PyMVA_Torch_Regression
• projectroot.tmva.pymva.test.PyMVA_Torch_Classification
• projectroot.tmva.pymva.test.PyMVA_Torch_Multiclass
• projectroot.tmva.pymva.test.gtest_tmva_pymva_test_TestRModelParserPyTorch

[phsft-bot]

Build failed on ROOT-performance-centos8-multicore/soversion. Running on olbdw-01.cern.ch:/data/sftnight/workspace/root-pullrequests-build See console output.

Failing tests:

• projectroot.runtutorials.tutorial_rcanvas_rline.cxx

[github-actions[bot]]

Test Results

     5 files       5 suites   22h 6m 55s :stopwatch:  2 560 tests  2 558 :white_check_mark: 0 :zzz: 2 :x: 11 954 runs  11 950 :white_check_mark: 0 :zzz: 4 :x:

For more details on these failures, see this check.

Results for commit fa0d5260.

:recycle: This comment has been updated with latest results.