Remove stack() call and warnings for external users in DNDarray.larray

[ClaudiaComito]

Description

Removing larray.setter warnings for users out of heat/core as the stack() call turns into a major memory leak.

Issue/s resolved: #810

Type of change

• Bug fix (non-breaking change which fixes an issue)

Due Diligence

• All split configurations tested
• Multiple dtypes tested in relevant functions
• Documentation updated (if needed)
• Updated changelog.md under the title "Pending Additions"

Does this change modify the behaviour of other functions? If so, which?

no

[codecov]

Codecov Report

Merging #811 (721566d) into master (5fc341b) will increase coverage by 4.43%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #811      +/-   ##
==========================================
+ Coverage   90.83%   95.27%   +4.43%     
==========================================
  Files          64       64              
  Lines        8961     8956       -5     
==========================================
+ Hits         8140     8533     +393     
+ Misses        821      423     -398     

Flag	Coverage Δ
gpu	94.40% <100.00%> (?)
unit	90.84% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
heat/core/dndarray.py	96.79% <100.00%> (+0.42%)	⬆️
heat/core/factories.py	100.00% <0.00%> (+0.84%)	⬆️
heat/core/statistics.py	97.60% <0.00%> (+0.85%)	⬆️
heat/core/linalg/basics.py	94.35% <0.00%> (+1.59%)	⬆️
heat/utils/data/partial_dataset.py	94.35% <0.00%> (+2.05%)	⬆️
heat/core/tests/test_suites/basic_test.py	96.11% <0.00%> (+4.85%)	⬆️
heat/core/communication.py	96.73% <0.00%> (+6.90%)	⬆️
heat/nn/data_parallel.py	94.48% <0.00%> (+10.34%)	⬆️
heat/core/devices.py	97.77% <0.00%> (+11.11%)	⬆️
... and 1 more

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