Upgrade to golangci-lint v2 for improved linting

Noteworthy changes in golangci-lint v2:

* New config format (migrated with `migrate` command)
* Default timeout is now 0 instead of 1 minute.

Also fixes issue reported by golangci-lint v2:

* Same error string formatting.

Author: jorbaum

scripts/subtests/lint

@@ -9,7 +9,7 @@ set +e
 golangci_lint_executable=$(which golangci-lint)
 set -e
 if [ -z "${golangci_lint_executable}" ] || [ ! -x "${golangci_lint_executable}" ]; then
-  go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest
+  go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@latest
 fi
 
 pushd "${SCRIPT_DIR}/../../src" > /dev/null

src/.golangci.yml

@@ -1,7 +1,10 @@
+version: "2"
+
 run:
-  # Timeout for analysis, e.g. 30s, 5m.
-  # Default: 1m
+  # Timeout full work, e.g. 30s, 5m.
+  # Default: none
   timeout: 5m
+
 linters:
   enable:
     # Checks for non-ASCII identifiers
@@ -10,9 +13,28 @@ linters:
     - gocyclo
     # Inspects source code for security problems.
     - gosec
+  exclusions:
+    generated: lax
+    presets:
+      - comments
+      - common-false-positives
+      - legacy
+      - std-error-handling
+    paths:
+      - third_party$
+      - builtin$
+      - examples$
 
 issues:
   # Disable max issues per linter.
   max-issues-per-linter: 0
   # Disable max same issues.
   max-same-issues: 0
+
+formatters:
+  exclusions:
+    generated: lax
+    paths:
+      - third_party$
+      - builtin$
+      - examples$

src/internal/ingress/listener.go

@@ -94,7 +94,7 @@ func (l *StatsdListener) parseStat(data string) (*loggregator_v2.Envelope, error
 	parts := statsdRegexp.FindStringSubmatch(data)
 
 	if len(parts) == 0 {
-		return nil, fmt.Errorf("Input line '%s' was not a valid statsd line.", data)
+		return nil, fmt.Errorf("input line '%s' was not a valid statsd line", data)
 	}
 
 	// parts[0] is complete matched string