irule to redirect traffic as well as changing the URL

Not sure why you are checking the URI for anything since this seems to be based on the host name. You should be able to:

when HTTP_REQUEST { 
log local0. "Host: [HTTP::host]"
if { [string tolower [HTTP::host]] equals "test.abc.com.int.xyz.com"} {
    HTTP::header replace "Host" "www.abc.com"
    pool YYYY 
    log local0. "    Setting Pool: YYYY"
    else {
    pool XXXX
    log local0. "    Setting Pool: XXXX"
    }
}