[dfsan] Remove realloc from done_abilist.txt

Summary:
Currently, realloc is marked as "discard" in done_abilist.txt. As discussed in PR#45583, this is probably not the expected behavior; a custom wrapper seems to be required. Since this wrapper has not been implemented yet, realloc should not be in the done_abilist.txt file so that a warning is displayed when it is called.

Reviewers: kcc, pcc, vitalybuka

Reviewed By: vitalybuka

Subscribers: #sanitizers

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D78379