perf(cli): optimize CPU consumption of help pages (#9607)

This change reduces the CPU consumption of --help by ~50%.

Also, this change removes ANSI escape codes from our golden files. I
don't think those were worth the inability to parallelize golden file tests and
global state fragility.

cli/cliui/agent_test.go

@@ -340,7 +340,7 @@ func TestAgent(t *testing.T) {
 				line := s.Text()
 				t.Log(line)
 				if len(tc.want) == 0 {
-					require.Fail(t, "unexpected line: "+line)
+					require.Fail(t, "unexpected line", line)
 				}
 				require.Contains(t, line, tc.want[0])
 				tc.want = tc.want[1:]