fix(32bit): make pack compatible with 32bit PHP

[susnux]

• Regression from feat(security): add configurable IPv6 subnet for BFP and throttling #52223

Summary

The P formatter is 64bit only - we need to manually pack the 64bit.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[come-nc]

https://github.com/nextcloud/server/actions/runs/14636364753 let’s see

[come-nc]

@susnux CI failed:

There were 2 failures:

1) Test\Security\Normalizer\IpAddressTest::testGetSubnet with data set #5 ('2001:0db8:0000:0000:0000:8a2e...0:7334', '2001:db8::/56')
Failed asserting that two strings are identical.
--- Expected
+++ Actual
@@ @@
-'2001:db8::/56'
+'2001::/56'

/__w/server/server/tests/lib/Security/Normalizer/IpAddressTest.php:64

2) Test\Security\Normalizer\IpAddressTest::testGetSubnet with data set #6 ('2001:db8:3333:4444:5555:6666:7777:8888', '2001:db8:3333:4400::/56')
Failed asserting that two strings are identical.
--- Expected
+++ Actual
@@ @@
-'2001:db8:3333:4400::/56'
+'2001:0:3333:4400::/56'

/__w/server/server/tests/lib/Security/Normalizer/IpAddressTest.php:64