Ensure that the `Map#get` hook does not flood the value profile bitmap

[fmeum]

Not directly related to this PR, but I wonder if mixing in lowerBoundKey and upperBoundKey to the hookIds would create unnecessary many IDs if the map content is not stable.

Originally posted by @bertschneider in https://github.com/CodeIntelligenceTesting/jazzer/issues/353#issuecomment-1062644234