Bluetooth: host: Fix DB hash calculation

When hashing attributes for the UUID cases:
    BT_UUID_GATT_PRIMARY_VAL
    BT_UUID_GATT_SECONDARY_VAL
    BT_UUID_GATT_INCLUDE_VAL
    BT_UUID_GATT_CHRC_VAL
    BT_UUID_GATT_CEP_VAL

where (handle || UUID || value) is to be hashed, the worst case size of
attribute value can be deduced from the associated union that describes
all the attribute values in the given cases.

Update the data array to accommodate for the worst case size.

Fixes #39131

Signed-off-by: Thomas Ebert Hansen <thoh@oticon.com>