meson: Drop legacy 'verify-signature' option

Currently there are two options for the image signature verification:
- 'verify-signature' (legacy),
- 'verify-full-signature' (current).

Drop legacy option and let the current one take its place.

Change-Id: Ia205424395179fd190e3d055159beca93cff0545
Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
diff --git a/meson.options b/meson.options
index d14ed3b..b088a8d 100644
--- a/meson.options
+++ b/meson.options
@@ -17,14 +17,8 @@
 
 option('tests', type: 'feature', description: 'Build tests')
 
-# This option is considered legacy, therefore there is no PACKAGECONFIG feature for disabling it in the recipe.
-# Functionality of this option is superseded by the 'verify-full-signature' option.
-# Option will be removed 4Q 2023
-option('verify-signature', type: 'feature', value: 'disabled',
-    description: 'LEGACY: Use verify-full-signature instead. Enable image signature validation.')
-
-option('verify-full-signature', type: 'feature', value: 'enabled',
-    description: 'Enable image full signature validation.')
+option('verify-signature', type: 'feature', value: 'enabled',
+    description: 'Enable image signature validation.')
 
 option(
     'usb-code-update', type: 'feature', value: 'enabled',