Add autocomplete off to LDAP login form

Some security tools will flag the absence of the autocomplete flag as a
possible security issue, as it could allow for passwords to be saved and
automatically filled in on shared computers. While most browsers will
ignore the presence of this field now and allow autocompletion anyway,
it doesn't hurt to have this here to avoid this scenario anyways.

Change-Id: I41c4a6ba0461a2494a2e64f017fa163967c6f5db

resources/com/google/gerrit/httpd/auth/ldap/LoginForm.html

diff --git a/resources/com/google/gerrit/httpd/auth/ldap/LoginForm.html b/resources/com/google/gerrit/httpd/auth/ldap/LoginForm.html
index 39900e8..593ea45 100644
--- a/resources/com/google/gerrit/httpd/auth/ldap/LoginForm.html
+++ b/resources/com/google/gerrit/httpd/auth/ldap/LoginForm.html
@@ -21,7 +21,7 @@
     <div id="gerrit_body" class="gerritBody">
       <h1>Sign In to Gerrit Code Review at <span id="hostName">example.com</span></h1>
       <div id="error_message">Invalid username or password.</div>
-      <form method="POST" action="#" id="login_form" onsubmit="return shouldSubmit()">
+      <form method="POST" action="#" id="login_form" autocomplete="off" onsubmit="return shouldSubmit()">
         <table style="border: 0;">
         <tr>
           <th>Username</th>