OAK-12378: Avoid allocating a new Comparator on every PropertyTemplate.compareTo() call

[nfsantos]

Motivation

OAK-12378: PropertyTemplate.compareTo() builds a fresh Comparator chain (3 objects, via comparingInt() + two thenComparing() calls) on every invocation instead of reusing a single instance. This method runs O(n log n) times when sorting templates during node writes, and is especially hot during compaction.

A Java Flight Recorder analysis found this allocation site responsible for ~81% of sampled allocation weight (~705 GB of allocation pressure) — by far the largest source in the recording. During compaction on a 1.2 GB heap this contributed to significant GC stress: 77 old-generation collections consuming 41.2s within a 300s window (13.7%), plus 200 evacuation failures and 4 concurrent mode failures indicating heap exhaustion.

Summary

• PropertyTemplate.compareTo() allocated a new Comparator chain on every call. Hoist it into a static final field so it's built once.

Test plan

• No behavior change; existing PropertyTemplate tests cover compareTo().