[BOLT] Return proper minimal alignment from BF (#67707)

Currently minimal alignment of function is hardcoded to 2 bytes.
Add 2 more cases:
1. In case BF is data in code return the alignment of CI as minimal
alignment
2. For aarch64 and riscv platforms return the minimal value of 4 (added
test for aarch64)
Otherwise fallback to returning the 2 as it previously was.