Revert "[llvm-cov] Look up object files using debuginfod"

This reverts commit efbc8bb1.

This change is causing failures when detecting curl on several build bots:
 - https://lab.llvm.org/buildbot/#/builders/247/builds/884
 - https://lab.llvm.org/buildbot/#/builders/231/builds/7688
 - https://lab.llvm.org/buildbot/#/builders/121/builds/27389
 - https://lab.llvm.org/buildbot/#/builders/230/builds/8464
 - https://lab.llvm.org/buildbot/#/builders/57/builds/24209
 - https://lab.llvm.org/buildbot/#/builders/127/builds/42722