Tests: retire pending-rebuild, which nothing has been gated behind for a day

The feature held the shared tests of features the fork hadn't rebuilt yet.
All nine are built and the last gate came off with per-domain directories,
so the feature was defined and documented but gated nothing.

The crate builds and holds the same tests without it: 113 by default, 118
with postgres, mysql and redis. SPEC §2.2b keeps its account of the first
import and now says when the gates came off, so a spec that still describes
a suite as gated reads as the record of its own date, which is what
monitoring.md's gate table already calls itself.

docs/spec/SPEC.md

@@ -132,7 +132,10 @@ repository. Instead:
   default: the OIDC-directory, tenant and archiving suites; the four
   telemetry suites (alerts, metrics, tracing, webhooks); and the LLM parts of
   the spam-filter suite. Each gate carries an `inbuxa: pending-rebuild` comment
-  and comes off when its feature is rebuilt.
+  and comes off when its feature is rebuilt. All nine features were rebuilt by
+  2026-09-19, so every gate came off and the feature itself was removed from
+  `tests/Cargo.toml` that day. A spec that still describes a suite as gated is
+  describing the state at its own date.
 - Those gated suites are shared, AGPL test code that exercises Enterprise
   behavior. That makes them a clean source for the feature specs, and ready-made
   acceptance tests for the rebuilds.

tests/Cargo.toml

@@ -4,10 +4,9 @@ version = "0.16.22"
 edition = "2024"
 
 [features]
-# Tests for Enterprise features the fork hasn't rebuilt yet. Off by default, so
-# the crate compiles without them. Each gate is marked `inbuxa: pending-rebuild`,
-# and comes off when its feature's rebuild lands.
-pending-rebuild = []
+# `pending-rebuild` held the shared tests of features the fork hadn't rebuilt
+# yet. All nine are built and every gate is off, so the feature went on
+# 2026-09-19 (docs/spec/SPEC.md §2.2b).
 #default = ["sqlite", "postgres", "mysql", "rocks", "s3", "redis", "nats", "azure", "foundationdb"]
 #default = ["sqlite", "postgres", "mysql", "rocks", "s3", "redis", "foundationdb"]
 default = ["rocks", "sqlite"]