build(alert): replace MutableBoolean with AtomicBoolean and remove dependency on Apache's commons-lang3

[c-dilks]

Remove org.apache.commons:commons-lang3 dependency, where we only use it for its MutableBoolean in one place; we replace MutableBoolean with java.util.concurrent.atomic.AtomicBoolean.

There's a dependency convergence conflict, however, so we still need to pin a version of commons-lang3 in the parent POM; the version number remains the same.