internal/sync: refactor HashTrieMap tests into per-op suites
This change does a minor refactor of the HashTrieMap tests to be better
organized into suites for each operation. It might be worthwhile to
deduplicate some code in here, but it's also helpful to see exactly
what's happening when something goes wrong.
Change-Id: I138515ee6de5aec5f3d38afe8a3bf3972afb2800
Reviewed-on: https://go-review.googlesource.com/c/go/+/606457
Auto-Submit: Michael Knyszek <mknyszek@google.com> Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>