Drop el8 builds (#188)

el8 has no builder image any more (the old almalinux8-rpmbuilder image can't be pulled) and el8 packages are no longer wanted.

- remove build/deploy almalinux8 pipelines
- remove el8 build entries from all package metadata
- drop almalinux/el8 from the metadata schema and tools/build

Requires unkin/terraform-git#110 applied (removes the build-almalinux8 required check).

Reviewed-on: #188
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>

tools/build

@@ -141,7 +141,7 @@ METADATA_SCHEMA = {
                     'minlength': 1,
                     'schema': {
                         'type': 'string',
-                        'allowed': ['almalinux/el8', 'almalinux/el9', 'fedora/42', 'fedora/43', 'fedora/44'],
+                        'allowed': ['almalinux/el9', 'fedora/42', 'fedora/43', 'fedora/44'],
                         'empty': False
                     }
                 },
@@ -583,7 +583,6 @@ def get_vendor_repo(distro: str) -> str:
     Map a distro path to its artifactapi rpm-vendor local repo name.
 
     Examples:
-        'almalinux/el8' -> 'rpm-vendor-el8'
         'almalinux/el9' -> 'rpm-vendor-el9'
         'fedora/42'     -> 'rpm-vendor-f42'
     """
@@ -1296,7 +1295,7 @@ class Builder:
         Discover all packages and their versions from metadata.yaml files.
 
         Args:
-            distro: Target distro (e.g., 'almalinux/el8', 'almalinux/el9', 'all')
+            distro: Target distro (e.g., 'almalinux/el9', 'all')
 
         Returns:
             List of PackageInfo objects
@@ -1387,7 +1386,7 @@ class Builder:
             release: Package release
             dry_run: If True, only show what would be done
             force: If True, build even if package exists
-            distro: Target distro (e.g., 'almalinux/el8', 'almalinux/el9', 'all')
+            distro: Target distro (e.g., 'almalinux/el9', 'all')
 
         Returns:
             True if build succeeded, False otherwise
@@ -1465,7 +1464,7 @@ class Builder:
             dry_run: If True, only show what would be done
             force: If True, build even if packages exist
             parallel: Number of parallel builds
-            distro: Target distro (e.g., 'almalinux/el8', 'almalinux/el9', 'all')
+            distro: Target distro (e.g., 'almalinux/el9', 'all')
 
         Returns:
             True if all builds succeeded, False otherwise
@@ -1935,7 +1934,7 @@ def build_all(
     dry_run: bool = typer.Option(False, "--dry-run", help="Show what would be built without building"),
     force: bool = typer.Option(False, "--force", help="Build even if packages exist in registry"),
     parallel: int = typer.Option(4, help="Number of parallel builds"),
-    distro: str = typer.Option("almalinux/el9", help="Target distro (almalinux/el8, almalinux/el9, or 'all' for all distros)"),
+    distro: str = typer.Option("almalinux/el9", help="Target distro (almalinux/el9, or 'all' for all distros)"),
     native: bool = typer.Option(False, "--native", help="Force native build (skip Docker even if available)"),
     buildah: bool = typer.Option(False, "--buildah", help="Force Buildah build (requires Buildah)"),
     verbose: bool = typer.Option(False, "--verbose", "-v", help="Enable verbose logging")