battery status: Remove battery-insecure-context.html. (#32556)

This test does not reflect either the current spec or any implementation.

w3c/battery#30 removed the bits from the spec that mandated throwing a
SecurityError when the API was used in an insecure origin. Blink does not
perform any checks for a security context anyway, although the plan is to
switch spec and implementation to using [SecureContext] in the future, as
tracked in w3c/battery#15.
diff --git a/battery-status/battery-insecure-context.html b/battery-status/battery-insecure-context.html
deleted file mode 100644
index 336a094..0000000
--- a/battery-status/battery-insecure-context.html
+++ /dev/null
@@ -1,27 +0,0 @@
-<!DOCTYPE html>
-<meta charset="utf-8">
-<title>Battery Test: navigator.getBattery() shall throw "SecurityError" in an insecure context</title>
-<link rel="author" title="Intel" href="http://www.intel.com">
-<link rel="help" href="https://www.w3.org/TR/battery-status/">
-<script src="/resources/testharness.js"></script>
-<script src="/resources/testharnessreport.js"></script>
-<style>
-  #note {
-    background-color: #fef1b5;
-    border: solid 1px #cdab2d;
-    padding: 5px;
-    margin: 15px;
-    display: block;
-  }
-</style>
-<div id="note">
-  Run test in an insecure context, e.g. http://example.com/.
-</div>
-
-<script>
-
-promise_test(t => {
-  return promise_rejects_dom(t, 'SecurityError', navigator.getBattery());
-}, "navigator.getBattery() shall throw a 'SecurityError' in an insecure context");
-
-</script>