third_party: delete autoComplete.js

The code using autoComplete.js was deleted in golang.org/cl/279133, so
delete the code. It was originally copied from
https://github.com/TarekRaafat/autoComplete.js. The non-minimized file
was deleted in golang.org/cl/340389 but the min files didn't seem to
be deleted around that time.

For golang/go#61399

Change-Id: I04f6437f8ba0c0a6a3972c1e52933d2478ae03ff
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/552115
kokoro-CI: kokoro <noreply+kokoro@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

Author: matloob

Diff for: third_party/autoComplete.js/LICENSE

@@ -6,5 +6,5 @@ package thirdparty
 
 import "embed"
 
-//go:embed autoComplete.js/* dialog-polyfill/*
+//go:embed dialog-polyfill/*
 var FS embed.FS

Diff for: third_party/autoComplete.js/autoComplete.min.js

@@ -8,7 +8,6 @@ import "testing"
 
 func TestFS(t *testing.T) {
 	for _, f := range []string{
-		"autoComplete.js/autoComplete.min.js",
 		"dialog-polyfill/dialog-polyfill.js",
 	} {
 		if _, err := FS.Open(f); err != nil {