chore(alpine): drop the deprecated Alpine 3.22 slot (#213)

## Why

Alpine 3.22 is deprecated and should be dropped.

It was never a published slot to begin with.
`local.rpkgs_slots` in `cdn.tf` enumerates eight distros and alpine322 is not one of them, so `UNION_SLOTS` never gated per-minor rewriting for it.
The website's `DistroId` union lists the same eight.
Every request to the slot therefore fell through to the flat index, which holds R 4.5 builds.

## Evidence

The fleet-wide routing verification (pipeline 12591, `verify_routing=all`) measured this end to end.

Across all 16 published slots, both architectures, three R minors and both contractual URL forms: **1056 of 1056 install-and-load checks passed.**

Every failure in the run was alpine322, identical on amd64 and arm64:

```
amd64/alpine322 R 4.4 via arch|generic|flat:  8 of 11
amd64/alpine322 R 4.6 via arch|generic|flat: 10 of 11
arm64/alpine322 R 4.4 via arch|generic|flat:  8 of 11
arm64/alpine322 R 4.6 via arch|generic|flat: 10 of 11
```

The tell is that all three forms agree.
On a routed slot `arch` and `generic` diverge from `flat`, because that divergence *is* the routing.
On alpine322 there is nothing to diverge from.
R 4.5 clients were 11 of 11 on every form, because flat happens to be what they need.

The data itself is not broken, only unreachable.
`alpine322/contrib/4.4/data.table_1.18.6.1.tar.gz` is genuinely `Built: R 4.4.3` and the 4.6 object is `Built: R 4.6.0`.
Correct objects, correct per-minor indexes, never served.

## What changed

- alpine-322 matrix rows and dropdown options removed from the 12 pipelines that carried them, so `=all` no longer fans out to a slot nobody can reach.
- `3.22` removed from the `OS_VERSION` dropdowns in `build-all-versions.yaml` and `repair-built-stamp.yaml`; the latter's default moves to `3.23`.
- Stale `3.22` examples updated in `local/packages-to-build.R`.

`crow lint .crow/` reports all 18 configs valid.

## Also done outside this diff

The six alpine-322 cron jobs are deleted from the Crow server, since a cron whose matrix row is gone keeps firing against nothing:

```
5   process-cran-updates-alpine-322-amd64     0 5/8 * * *
6   process-cran-updates-alpine-322-arm64     30 5/8 * * *
68  weekly-audit-missing-alpine-322-amd64     20 0 * * 0
69  weekly-audit-missing-alpine-322-arm64     30 0 * * 0
82  weekly-rebuild-missing-alpine-322-amd64   0 4 * * 0
83  weekly-rebuild-missing-alpine-322-arm64   10 4 * * 0
```

They are listed here so they can be recreated if this is ever reversed.

## Not done

The published objects and indexes under `amd64/alpine322` and `arm64/alpine322` are left in the bucket.
Deleting them is a separate decision, and nothing routes to them in the meantime.

Reviewed-on: #213

.crow/repair-built-stamp.yaml

@@ -16,7 +16,7 @@
 # pipeline here gates on a variable named after itself for exactly that reason.
 #
 #   crow pipeline create --branch main \
-#     --var repair_built_stamp=arm64 --var OS=alpine --var OS_VERSION=3.22 \
+#     --var repair_built_stamp=arm64 --var OS=alpine --var OS_VERSION=3.23 \
 #     --var R_VERSION=4.5.3 --var dry_run=true devxy/build-cran-binaries
 variables:
   # Gates this pipeline. A manual pipeline creation instantiates every file in
@@ -37,9 +37,8 @@ variables:
       - ubuntu
     default: alpine
   OS_VERSION:
-    description: 'OS image tag. Must match OS (alpine: 3.22/3.23/3.24; redhat: 8/9/10; ubuntu: jammy/noble/resolute).'
+    description: 'OS image tag. Must match OS (alpine: 3.23/3.24; redhat: 8/9/10; ubuntu: jammy/noble/resolute).'
     options:
-      - '3.22'
       - '3.23'
       - '3.24'
       - '8'
@@ -48,7 +47,7 @@ variables:
       - 'jammy'
       - 'noble'
       - 'resolute'
-    default: '3.22'
+    default: '3.23'
   R_VERSION:
     description: 'R version whose stamp the slot should advertise.'
     options: