Remove kIgnoreCertificateErrors in chrome/browser/banners

The switch --ignore-certificate-errors is frequently misused throughout
the codebase by tests that use an HTTPS EmbeddedTestServer to serve
URLs with custom hostname(s). Ignoring certificate errors is usually
incorrect and unnecessary; the better way is to configure the HTTPS
EmbeddedTestServer with the proper certificates.

This is done by configuring valid test certs using variously:
 * net::EmbeddedTestServer::CERT_TEST_NAMES,
 * generated test certificate configured by:
      * net::EmbeddedTestServer::SetCertHostnames(),
      * manually setting `ServerCertificateConfig::dns_names`,
      * using the default ServerCertificateConfig configuration provided
        by content::BrowserTestBase with embedded_https_test_server().

Some tests were also using the switch entirely unnecessarily as they
were not using an HTTPS test server, or did not use custom hostnames.

This CL covers test files in:
chrome/browser/banners

This CL was uploaded by git cl split.

R=alancutter@chromium.org

Bug: 40147519
Change-Id: I6660e8b46357615ec2d2939bb71d0e1ebbcba212
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7143498
Auto-Submit: Lily Chen <chlily@chromium.org>
Reviewed-by: Alan Cutter <alancutter@chromium.org>
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1543507}