fix: Unify casing of select words and phrases (#1040)

Removed and unnecessary period, as well as correctly some words that
were capitalized when they shouldn't be.

---

UDENG-5683

gui/packages/ubuntupro/lib/l10n/app_en.arb

@@ -43,7 +43,7 @@
     "getUbuntuPro": "Get Ubuntu Pro",
     "learnMore": "Learn more",
 
-    "ubuntuProEnabled": "Ubuntu Pro is enabled on this machine.",
+    "ubuntuProEnabled": "Ubuntu Pro is enabled on this machine",
     "ubuntuProEnabledInfo": "All Ubuntu WSL instances have access to Ubuntu Pro security features.",
     "manageUbuntuPro": "Manage Ubuntu Pro subscription",
     "detachPro": "Detach Ubuntu Pro",
@@ -70,12 +70,12 @@
     },
     "landscapeSetupManual": "Manual configuration",
     "landscapeSetupManualHint": "Register with your own Landscape server",
-    "landscapeSetupCustom": "Advanced Configuration",
+    "landscapeSetupCustom": "Advanced configuration",
     "landscapeSetupCustomHint": "Load a custom Landscape client configuration file",
     "landscapeFQDNLabel": "Landscape FQDN",
     "landscapeFQDNError": "Invalid FQDN. Format should be a hostname or IP address.",
     "landscapeFQDNSaaSError": "FQDN shouldn't be landscape.canonical.com.",
-    "landscapeKeyLabel": "Registration Key (optional)",
+    "landscapeKeyLabel": "Registration key (optional)",
     "landscapeSSLKeyLabel": "Server SSL public key (optional)",
     "landscapeFileLabel": "Config file path",
     "landscapeFileTooLarge": "Configuration file is too large",