meson option: make the insecure-disable-auth macro more accurate

The "auth" term is overloaded in meson option and macros. This commit
changes the macro from BMCWEB_INSECURE_DISABLE_AUTHENTICATION to
BMCWEB_INSECURE_DISABLE_AUTHX, given that if "insecure-disable-auth"
is enabled, both authentication and authorization are disabled.

Tested:
1. set 'insecure-disable-auth=enabled', no authz nor authn is performed,
no crash on AccountService as well.

Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
Change-Id: Iddca1f866d16346bcc2017338fa6f077cb89cef9
diff --git a/meson_options.txt b/meson_options.txt
index c81f185..e731ab3 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -264,8 +264,8 @@
     'insecure-disable-auth',
     type: 'feature',
     value: 'disabled',
-    description: '''Disable authentication on all ports. Should be set to false
-                    for production systems'''
+    description: '''Disable authentication and authoriztion on all ports.
+                    Should be set to false for production systems.'''
 )
 
 option(