[FL-3081] fbt: removed DEBUG_TOOLS & FAP_EXAMPLES flags (#2291)

* fbt: deprecated DEBUG_TOOLS & FAP_EXAMPLES flags
* fixes for PVS warnings
* scripts: fbt: fixed leaking PYTHONHOME

site_scons/commandline.scons

@@ -81,16 +81,6 @@ vars.AddVariables(
             "7",
         ],
     ),
-    BoolVariable(
-        "DEBUG_TOOLS",
-        help="Enable debug tools to be built",
-        default=False,
-    ),
-    BoolVariable(
-        "FAP_EXAMPLES",
-        help="Enable example applications to be built",
-        default=False,
-    ),
     (
         "DIST_SUFFIX",
         "Suffix for binaries in build output for dist targets",
@@ -232,6 +222,7 @@ vars.AddVariables(
             ("applications/system", False),
             ("applications/debug", False),
             ("applications/plugins", False),
+            ("applications/examples", False),
             ("applications_user", False),
         ],
     ),