Site Health: Improve the wording in plugin and theme version tests.

This displays a more appropriate message in case the site does not have any active plugins or installed themes.

Follow-up to [44986], [45099], [45336].

Props Presskopp, costdev, martin.krcho, Clorith, SergeyBiryukov.
Fixes #56134.

git-svn-id: https://develop.svn.wordpress.org/trunk@53816 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/class-wp-site-health.php

@@ -428,7 +428,7 @@ class WP_Site_Health {
 					'<p>%s</p>',
 					__( 'Your site has 1 active plugin, and it is up to date.' )
 				);
-			} else {
+			} elseif ( $plugins_active > 0 )  {
 				$result['description'] .= sprintf(
 					'<p>%s</p>',
 					sprintf(
@@ -441,6 +441,11 @@ class WP_Site_Health {
 						$plugins_active
 					)
 				);
+			} else {
+				$result['description'] .= sprintf(
+					'<p>%s</p>',
+					__( 'Your site does not have any active plugins.' )
+				);
 			}
 		}
 
@@ -591,7 +596,7 @@ class WP_Site_Health {
 					'<p>%s</p>',
 					__( 'Your site has 1 installed theme, and it is up to date.' )
 				);
-			} else {
+			} elseif ( $themes_total > 0 )  {
 				$result['description'] .= sprintf(
 					'<p>%s</p>',
 					sprintf(
@@ -604,6 +609,11 @@ class WP_Site_Health {
 						$themes_total
 					)
 				);
+			} else {
+				$result['description'] .= sprintf(
+					'<p>%s</p>',
+					__( 'Your site does not have any installed themes.' )
+				);
 			}
 		}