Small performance/readability improvments when iterating dictionnary with keys()

Based on pylint's message ``consider-iterating-dictionary`` suggestion.
Surprisingly using a dict or set comprehension instead of a new temp var is
actually consistently slower here, which was not intuitive for me.

```python
from timeit import timeit

families = {1: {"testcase": [1, 2, 3, 5, 8]}}
attrs = {1: "a", 2: "b", 3: "c", 4: "d", 5: "e", 6: "f", 7: "g", 8: "h"}

class Old:
    def old(self):
        self.attrs = attrs
        temp_attrs = {}
        for key in self.attrs.keys():
            if key in families[1]["testcase"]:
                temp_attrs[key] = self.attrs[key]
        self.attrs = temp_attrs

class OldBis:
    def old(self):
        self.attrs = attrs
        temp_attrs = {}
        for key in self.attrs:
            if key in families[1]["testcase"]:
                temp_attrs[key] = self.attrs[key]
        self.attrs = temp_attrs

class New:
    def new(self):
        self.attrs = attrs
        self.attrs = { # Even worse with k: v for k in self.attrs.items()
            k: self.attrs[k] for k in self.attrs if k in families[1]["testcase"]
        }

if __name__ == "__main__":
    n = 1000000
    print(f"Old: {timeit(Old().old, number=n)}")
    print(f"Just removing the keys(): {timeit(OldBis().old, number=n)}")
    print(f"List comp, no temp var: {timeit(New().new, number=n)}")
```

Result:
Old: 0.9493889989680611
Just removing the keys(): 0.9042672360083088
List comp, no temp var: 0.9916125109884888

It's also true for the other example with similar benchmark, but the exact
code probably does not need to be in the commit message.

Author: Pierre-Sassoulas

pyproject.toml

@@ -183,7 +183,6 @@ disable= [
     "comparison-with-callable",
     "comparison-with-itself",
     "condition-evals-to-constant",
-    "consider-iterating-dictionary",
     "consider-using-dict-items",
     "consider-using-enumerate",
     "consider-using-from-import",

src/_pytest/junitxml.py

@@ -143,7 +143,7 @@ def record_testreport(self, testreport: TestReport) -> None:
         # Filter out attributes not permitted by this test family.
         # Including custom attributes because they are not valid here.
         temp_attrs = {}
-        for key in self.attrs.keys():
+        for key in self.attrs:
             if key in families[self.family]["testcase"]:
                 temp_attrs[key] = self.attrs[key]
         self.attrs = temp_attrs

src/_pytest/terminal.py

@@ -1267,7 +1267,7 @@ def _determine_main_color(self, unknown_type_seen: bool) -> str:
 
     def _set_main_color(self) -> None:
         unknown_types: List[str] = []
-        for found_type in self.stats.keys():
+        for found_type in self.stats:
             if found_type:  # setup/teardown reports have an empty key, ignore them
                 if found_type not in KNOWN_TYPES and found_type not in unknown_types:
                     unknown_types.append(found_type)