c001374636
C++20 introduced `contains` member functions for maps and sets for checking whether an element is present in the collection. Previously `count` function was often used in various ways. `contains` does not only express the intend of the code better but also does it in more unified way. This commit replaces all the occurences of the `count` with the `contains`. Tests: unit(dev) Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com> Message-Id: <b4ef3b4bc24f49abe04a2aba0ddd946009c9fcb2.1597314640.git.piotr@scylladb.com>