[CallGraph] Preserve call records vector when replacing call edge

Summary:
Try not to resize vector of call records in a call graph node when
replacing call edge. That would prevent invalidation of iterators
stored in the CG SCC pass manager's scc_iterator.

Reviewers: jdoerfert

Reviewed By: jdoerfert

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D84295