[CNV-75960] Add STP for Multi-Arch Boot Image Import and DataSource Lifecycle

STP for enableMultiArchBootImageImport feature testing on heterogeneous
clusters. Covers DataSource lifecycle, architecture labeling,
duplicate prevention, and cleanup validation.

Related: VIRTSTRAT-494
Parent STP: #12

Signed-off-by: Geetika Kapoor <gkapoor@redhat.com>

Author: geetikakay