Remove copyright notices in .py, .cpp and .hpp files

[berland]

Issue Having such a notice present in every file is visual noise and does not significantly increase protection against copyright infringement.

Approach

for file in `find . -name *.*pp`; do
    perl -0 -p -i -e 's/\/\*.*Copyright.*?\*\/\s*//is' $file
done

for file in `find . -name "*.py"`; do
    perl -0 -p -i -e 's/#\s+Copyright.*#\s+for more details.\s*//s' $file
done

Pre review checklist

• [x] Added appropriate release note label
• [x] PR title captures the intent of the changes, and is fitting for release notes.
• [x] Commit history is consistent and clean, in line with the contribution guidelines.

Adding labels helps the maintainers when writing release notes. This is the list of release note labels.