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

Following implementation of commit 219d5b5,
and to complement commit 8c4f98d
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>

Author: ABOSTM

tests/arch/arm/arm_irq_vector_table/irq-vector-table.ld

@@ -1,3 +1,10 @@
 /* SPDX-License-Identifier: Apache-2.0 */
 
 KEEP(*(_IRQ_VECTOR_TABLE_SECTION_SYMS))
+
+/*
+ * Some ARM platforms require this symbol to be placed after the IRQ vector
+ * table (like STM32F0). The symbol defined here is overriding the one in
+ * arch/arm/core/aarch32/vector_table.ld when the IRQ vector table is enabled.
+ */
+_vector_end = .;