gopls/internal/regtest: unskip Test_Issue38211

This test was originally skipped due to deadline exceeded errors. In the
time since, we've made performance improvements, fixed races, and
altered the regtests to remove arbitrary deadlines. Unskip it to see if
it still flakes.

For golang/go#44098
For golang/go#53878

Change-Id: I06530f2bc9c6883f415dc9147cfcbf260abb2a00
Reviewed-on: https://go-review.googlesource.com/c/tools/+/418898
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>

gopls/internal/regtest/diagnostics/diagnostics_test.go

@@ -636,8 +636,6 @@ var ErrHelpWanted error
 
 // Test for golang/go#38211.
 func Test_Issue38211(t *testing.T) {
-	t.Skipf("Skipping flaky test: https://golang.org/issue/44098")
-
 	testenv.NeedsGo1Point(t, 14)
 	const ardanLabs = `
 -- go.mod --