[Profile] Fix gcov tests
Summary: The gcda need to be delete before running the binary to avoid to have an increasing "# of Runs" when a test is failing
Reviewers: vitalybuka, eugenis, marco-c
Reviewed By: marco-c
Subscribers: delcypher, llvm-commits, #sanitizers, sylvestre.ledru, marco-c
Differential Revision: https://reviews.llvm.org/D52456