tests: arch: arm: arm-irq-vector-table: define _vector_end

Following implementation of commit 219d5b5a,
and to complement commit 8c4f98d2
it is also necessary define _vector_end in
test specific arm-irq-vector-table.ld

Fixes #47273

Signed-off-by: Alexandre Bourdiol <alexandre.bourdiol@st.com>