Golangci lint fixes (#195)

* Add golangci-lin as make target
* Fix: could omit type ... from declaration; it will be inferred from the right-hand side (staticcheck)
* Fix func intArrayContains is unused (unused)
* Fix: could use strings.ReplaceAll instead (staticcheck)
* Fix: could expand call to math.Pow (staticcheck)
* Fix: could use tagged switch on `...` (staticcheck)
* Fix: Error return value of `...` is not checked (errcheck)
* Fix: ineffectual assignment to err (ineffassign)
* Fix: There is no need to wait for command completion
* Add cpustat, diskstat and schedstat config
* Use slices to exclude metrics
* Replaced stringArrayContains by slices.Contains
* Replace m[k]=v loop with maps.Copy
* Use module slices from the standard library. Remove use of golang.org/x/exp/slices
* Use SplitSeq and max to modernize code

collectors/beegfsstorageMetric.go

@@ -17,6 +17,7 @@ import (
 	"os/exec"
 	"os/user"
 	"regexp"
+	"slices"
 	"strconv"
 	"strings"
 	"time"
@@ -54,7 +55,9 @@ func (m *BeegfsStorageCollector) Init(config json.RawMessage) error {
 		"storInf", "unlnk"}
 
 	m.name = "BeegfsStorageCollector"
-	m.setup()
+	if err := m.setup(); err != nil {
+		return fmt.Errorf("%s Init(): setup() call failed: %w", m.name, err)
+	}
 	m.parallel = true
 	// Set default beegfs-ctl binary
 
@@ -71,8 +74,7 @@ func (m *BeegfsStorageCollector) Init(config json.RawMessage) error {
 	//create map with possible variables
 	m.matches = make(map[string]string)
 	for _, value := range storageStat_array {
-		_, skip := stringArrayContains(m.config.ExcludeMetrics, value)
-		if skip {
+		if slices.Contains(m.config.ExcludeMetrics, value) {
 			m.matches["other"] = "0"
 		} else {
 			m.matches["beegfs_cstorage_"+value] = "0"