api: remove status cache validators

tests/test_http_api_contract.py

@@ -284,7 +284,7 @@ def test_http_error_fixture_and_known_error_codes_are_stable():
         assert error_code in source
 
 
-def test_status_endpoint_supports_field_selection_and_cache_headers():
+def test_status_endpoint_supports_field_selection():
     source = firmware_source()
 
     assert 'server.hasArg("fields")' in source
@@ -293,13 +293,6 @@ def test_status_endpoint_supports_field_selection_and_cache_headers():
     assert '"invalid_field"' in source
     assert 'Unknown field' in source
     assert 'server.send(400, "application/json", errorOutput)' in source
-    assert 'server.sendHeader("ETag", etag)' in source
-    assert 'server.sendHeader("Last-Modified", lastStatusModified)' in source
-    assert 'server.sendHeader("Cache-Control", "no-cache")' in source
-    assert 'server.header("If-None-Match")' in source
-    assert 'server.header("If-Modified-Since")' in source
-    assert 'server.send(304)' in source
-    assert 'server.collectHeaders(statusCacheHeaders, 2)' in source
 
 
 def test_embedded_webui_uses_partial_status_for_overview_polling():