[scudo] Adjust PROT_MTE page count for secondary allocator (#192202)

Secondary allocator currently mmaps 4 pages as PROT_MTE in case MTE is
enabled in the allocator for Aarch64.
Since only the headers are tagged, this is unnecessary, two pages are
sufficient in worst case scenario.

GitOrigin-RevId: 8c10815313231c629999a3f54b48f80eb6715e94
1 file changed