Improve eBPF memory usage

[thiagoftsm]

Summary

Adjust kernel-collector code improving memory usage in kernel ring.

Test Plan

1. Get binaries according to your C library from [this](ADD ACTIONS LINK HERE) link and extract them inside a directory, for example: ../artifacts.
   You can also get everything for glibc [here](UPLOAD FILE WITH ALL BINARIES TO SIMPLIFY REVIEWERS).

2. Extract them running:

   $ for i in `ls *.zip`; do unzip $i; rm .gitkeep ; rm $i; done
   $ for i in `ls *.xz`; do tar -xf $i; rm $i* ; done

3. Compile branch an run the following tests:

   # make clean; make tester
   # for i in `seq 0 3`; do ./kernel/legacy_test --netdata-path ../artifacts --content --iteration 1 --pid $i --log-path file_pid$i.txt; done

4. Every test should ends with Success, unless you do not have a specific target (function) available.

Additional information

This PR was tested on:

Linux Distribution	Environment	Kernel Version	Real Parent	Parent	All PIDs	Without PIDs
LINUX DISTRIBUION	Bare metal/VM	uname -r