chore: change the prompt of pax extension in configure help

The --enable-pax configuration option defaults to 'yes'. so in the
default help information, we need to display the '--disable-pax' option

Author: gongxun0928

configure

@@ -1618,7 +1618,7 @@ Optional Features:
                           library)
   --disable-preload-ic-module
                           disable preload interconnect module
-  --enable-pax            enable pax support
+  --disable-pax           disable pax support
   --disable-thread-safety disable thread-safety in client libraries
   --enable-openssl-redirect
                           enable redirect openssl interface to internal

contrib/pax_storage/doc/README.md

@@ -21,7 +21,7 @@ PAX has the following features:
 
 ### Build PAX
 
-PAX will be built with `--enable-pax` when users building the Cloudberry.
+PAX will be built by default when users are building the Cloudberry.
 
 ### Build debug version