fix(metrics): Replace invalid tag values with an empty string instead of _ (#2773)

Author: markushi

sentry_sdk/metrics.py

@@ -55,7 +55,7 @@
 
 _in_metrics = ContextVar("in_metrics", default=False)
 _sanitize_key = partial(re.compile(r"[^a-zA-Z0-9_/.-]+").sub, "_")
-_sanitize_value = partial(re.compile(r"[^\w\d_:/@\.{}\[\]$-]+", re.UNICODE).sub, "_")
+_sanitize_value = partial(re.compile(r"[^\w\d_:/@\.{}\[\]$-]+", re.UNICODE).sub, "")
 _set = set  # set is shadowed below
 
 GOOD_TRANSACTION_SOURCES = frozenset(

tests/test_metrics.py

@@ -822,7 +822,7 @@ def test_tag_normalization(
 
     assert len(m) == 3
     assert m[0][4] == {
-        "foo-bar": "_$foo",
+        "foo-bar": "$foo",
         "release": "fun-release@1.0.0",
         "environment": "not-fun-env",
     }