[202205][generate_dump] Revert "Revert generate_dump optimization PR's …

…#2581", add fixes for empty /dump forder and symbolic links (#2711)

* Revert "[202205] Revert the show-techsupport optimization PR's (#2581)"

This reverts commit dddd6c5.

* [generate_dump] Fix for empty /dump folder

Signed-off-by: vadymhlushko-mlnx <vadymh@nvidia.com>

* [generate_dump] Fix for symlinks in collect_mellanox_dfw_dumps()

Signed-off-by: vadymhlushko-mlnx <vadymh@nvidia.com>

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Signed-off-by: vadymhlushko-mlnx <vadymh@nvidia.com>