arch: remove `z_arch_esf_t`

The exception stack frame type `z_arch_esf_t` had been deprecated
since #73593 for 2 releases, it is not used in the kernel since, and
applications/drivers should have been updated to use the
`struct arch_esf` now, remove it.

Signed-off-by: Yong Cong Sin <ycsin@meta.com>
Signed-off-by: Yong Cong Sin <yongcong.sin@gmail.com>