[CaptureTracking] Replace hardcoded constant to option. NFC.

The motivation is to be able to play with the option and change if it is required.

Reviewers: fedor.sergeev, apilipenko, rnk, jdoerfert
Reviewed By: fedor.sergeev
Subscribers: hiraditya, dantrushin, llvm-commits
Differential Revision: https://reviews.llvm.org/D78624