languages: Do not expose unnecessary captures from tasks (#19625)

This tackles an issue with us exposing unnecessary env variables in
environment which are not actually needed for tasks themselves (and may
have little utility), yet come into the way of ssh remoting.

/cc @ConradIrwin 

Release Notes:

- N/A

crates/languages/src/python/runnables.scm

@@ -7,7 +7,7 @@
             (attribute (identifier) @_superclass)]
         )
         (#eq? @_superclass "TestCase")
-    ) @python-unittest-class
+    ) @_python-unittest-class
     (#set! tag python-unittest-class)
 )
 
@@ -24,7 +24,7 @@
                 (function_definition
                     name: (identifier) @run @_unittest_method_name
                     (#match? @_unittest_method_name "^test.*")
-                ) @python-unittest-method
+                ) @_python-unittest-method
                 (#set! tag python-unittest-method)
             )
         )