all: replace Split in loops with more efficient SplitSeq
Find these replacements through https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/modernize.
Change-Id: If88fe0e109b7c7557bfb3d3ffc15271af1ab5856
Reviewed-on: https://go-review.googlesource.com/c/go/+/668437 Reviewed-by: Sean Liao <sean@liao.dev>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Sean Liao <sean@liao.dev> Reviewed-by: David Chase <drchase@google.com>