meson: Disable 'verify-signature' option by default

Currently the 'verify-signature' option is enabled by default, and
there is no way to disable it via recipe PACKAGECONFIG.
As a result 'Software::Version::Error::InvalidSignature' is generated
on unsigned updates even if user did not enable signature verification
feature.
Disable 'verify-signature' option by default to correct the issue.
If user enables signature verification feature the option
'verify-full-signature' is enabled which provides desired functionality.

Change-Id: Ie143bf7922115ec529a0d30fb68e7c26bce0be77
Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
diff --git a/meson_options.txt b/meson_options.txt
index a356b5b..d14ed3b 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -17,7 +17,10 @@
 
 option('tests', type: 'feature', description: 'Build tests')
 
-option('verify-signature', type: 'feature', value: 'enabled',
+# 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+# Functionality of this option is superseded by the 'verify-full-signature' option.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',