kernel-clk6.12: move base kernel Obsoletes to -default package

Move 'Obsoletes: kernel = ...' from the base metapackage to the
kernel-clk6.12-default package. This ensures that:

1. Users upgrading from old kernel-6.12.* packages will automatically get
   kernel-clk6.12-default installed (via Obsoletes)

2. kernel-clk6.12-default takes ownership of /etc/sysconfig/kernel to ensure
   kernel-clk6.12 variants remain the default kernel on the system

3. Without this, users with old CIQ kernels AND stock Rocky kernels might end
   up with stock Rocky kernels becoming the default after upgrade

The kernel-clk6.12-debug metapackage still keeps its Obsoletes since there
is no kernel-clk6.12-debug-default package.

Author: bmastbergen

ciq/SPECS/kernel-clk6.12.spec

@@ -1045,13 +1045,6 @@ Patch999999: linux-kernel-test.patch
 
 # END OF PATCH DEFINITIONS
 
-Obsoletes: kernel = 6.12.15
-Obsoletes: kernel = 6.12.30
-Obsoletes: kernel = 6.12.43
-Obsoletes: kernel = 6.12.63
-Obsoletes: kernel = 6.12.74
-Obsoletes: kernel = 6.12.77
-
 %description
 The kernel meta package
 
@@ -1412,6 +1405,12 @@ Requires: %{package_name} = %{?epoch:%{epoch}:}%{specversion}-%{release}
 Requires(posttrans): %{package_name}-core = %{?epoch:%{epoch}:}%{specversion}-%{release}
 Provides: kernel-provider(default)
 Conflicts: kernel-provider(default)
+Obsoletes: kernel = 6.12.15
+Obsoletes: kernel = 6.12.30
+Obsoletes: kernel = 6.12.43
+Obsoletes: kernel = 6.12.63
+Obsoletes: kernel = 6.12.74
+Obsoletes: kernel = 6.12.77
 %description default
 This package sets kernel-%{pkg_suffix} as the default kernel for the system
 by modifying /etc/sysconfig/kernel. When installed, only new kernels of the