Summary:
To save memory usage, I have tweaked the ELFIO library:
1) It now has an option to skip loading segments (the sections are all we need).
2) It no longer loads the data of PROGBITS sections, which contain program specific information, including DWARF info. Getting the symbols do not require these sections, which take up a lot of memory.

On one binary, this brought the memory requirements (RSS) from 278 MB down to 63 MB, over 4x memory savings.

Test Plan: Existing tests

Reviewers: zasgar, yzhao, #engineering

Reviewed By: zasgar, #engineering

JIRA Issues: PL-1645

Differential Revision: https://phab.corp.pixielabs.ai/D4016

GitOrigin-RevId: c25b879706e3d31623805c08cc5b1bbee8883685