[statsdreceiver] add test for empty statsd tags

we see some payloads with completely empty tags, which we can
safely ignore. there is already support for this in the receiver;
this simply adds a test to track future regressions on this behavior.

.chloggen/b_statsd-empty-tags.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: statsdreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: add test coverage for cases where tags are empty
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [32337]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

receiver/statsdreceiver/internal/protocol/statsd_parser_test.go

@@ -71,6 +71,15 @@ func Test_ParseMessageToMetric(t *testing.T) {
 				false,
 				"c", 0, nil, nil, 0),
 		},
+		{
+			name:  "integer counter with empty tags",
+			input: "test.metric:42|c|#,,,",
+			wantMetric: testStatsDMetric(
+				"test.metric",
+				42,
+				false,
+				"c", 0, nil, nil, 0),
+		},
 		{
 			name:  "integer counter",
 			input: "test.metric:42|c",