[sheriff] Disable Network/DictationCommandsTest.Help/0

This test has been flaking on and off on the
Linux Chromium OS ASan LSan Tests (1) bot. See below for an example
build.

https://ci.chromium.org/ui/p/chromium/builders/ci/Linux%20Chromium%20OS%20ASan%20LSan%20Tests%20(1)/44771/overview

Bug: 1348608
Change-Id: Ic0e28a53e026096e527161f1191dd9a237d4b150
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3793487
Owners-Override: Tom Lukaszewicz <tluk@google.com>
Commit-Queue: Juanmi Huertas <juanmihd@chromium.org>
Auto-Submit: Thomas Lukaszewicz <tluk@chromium.org>
Reviewed-by: Juanmi Huertas <juanmihd@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1034776}

chrome/browser/ash/accessibility/dictation_browsertest.cc

@@ -938,7 +938,13 @@ IN_PROC_BROWSER_TEST_P(DictationCommandsTest, MacroSucceededMetric) {
                                        /*expected_bucket_count=*/1);
 }
 
-IN_PROC_BROWSER_TEST_P(DictationCommandsTest, Help) {
+// Flaky on Linux (crbug.com/1348608).
+#if BUILDFLAG(IS_LINUX)
+#define MAYBE_Help DISABLED_Help
+#else
+#define MAYBE_Help Help
+#endif
+IN_PROC_BROWSER_TEST_P(DictationCommandsTest, MAYBE_Help) {
   SendFinalResultAndWait("help");
 
   // Wait for the help URL to load.