tests/flash_disk: Expand scenarios to cover no erase device

The commit adds overlay for native_posix and modifies testcase.yaml
to allow testing CONFIG_DISK_DRIVER_FLASH with device that
do not have erase requirement.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

tests/drivers/disk/disk_access/boards/native_posix_no_explicit_erase.overlay

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&flashcontroller0 {
+	reg = <0x00000000 DT_SIZE_K(1024)>;
+};
+
+&flash0 {
+	reg = <0x00000000 DT_SIZE_K(1024)>;
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		flashdisk_partition: partition@0 {
+			label = "flashdisk";
+			reg = <0x00000000 0x00100000>;
+		};
+	};
+};
+
+/ {
+	test_disk: storage_disk {
+		compatible = "zephyr,flash-disk";
+		partition = <&flashdisk_partition>;
+		disk-name = "NAND";
+		cache-size = <512>;
+	};
+};

tests/drivers/disk/disk_access/testcase.yaml

@@ -36,3 +36,11 @@ tests:
       - native_sim
   drivers.disk.stm32_sdhc:
     filter: dt_compat_enabled("st,stm32-sdmmc")
+  drivers.disk.simulator.no_explicit_erase:
+    extra_args: DTC_OVERLAY_FILE=boards/native_posix_no_explicit_erase.overlay
+    extra_configs:
+      - CONFIG_DISK_DRIVER_FLASH=y
+      - CONFIG_FLASH_SIMULATOR_EXPLICIT_ERASE=n
+    platform_allow:
+      - native_posix/native/64
+      - native_posix