Rust: accept last integration test changes

Also make `--learn` work with the nested qltest tests.

rust/ql/integration-tests/qltest/dependencies/functions.expected

@@ -1 +0,0 @@
-| test.rs:4:1:7:1 | foo |

rust/ql/integration-tests/qltest/dependencies/functions.nested.expected

@@ -0,0 +1 @@
+| test.rs:4:1:7:1 | fn foo |

rust/ql/integration-tests/qltest/lib/functions.expected

@@ -1 +0,0 @@
-| test.rs:1:1:1:11 | foo |

rust/ql/integration-tests/qltest/lib/functions.nested.expected

@@ -0,0 +1 @@
+| test.rs:1:1:1:11 | fn foo |

rust/ql/integration-tests/qltest/main/functions.expected

@@ -1,2 +0,0 @@
-| main.rs:1:1:1:12 | main |
-| test.rs:1:1:1:11 | foo |

rust/ql/integration-tests/qltest/main/functions.nested.expected

@@ -0,0 +1,2 @@
+| main.rs:1:1:1:12 | fn main |
+| test.rs:1:1:1:11 | fn foo |

rust/ql/integration-tests/qltest/test_qltest.py

@@ -6,16 +6,17 @@ import pytest
 # (which skips `qltest.{sh,cmd}`)
 
 @pytest.fixture(autouse=True)
-def default_options(codeql, pytestconfig):
+def default_options(codeql):
     codeql.flags.update(
         threads = 1,
         show_extractor_output = True,
         check_databases = False,
-        learn = pytestconfig.getoption("learn"),
+        learn = True,
     )
 
 @pytest.mark.parametrize("dir", ["lib", "main", "dependencies"])
-def test(codeql, rust, dir):
+def test(codeql, rust, expected_files, dir):
+    expected_files.add(f"{dir}/functions.expected", expected=".nested.expected")
     codeql.test.run(dir)
 
 def test_failing_cargo_check(codeql, rust):