Revert "metrics: add support for enabling metrics from env vars (ethereum#28118)"

This reverts commit e284083.

Author: devopsbo3

metrics/metrics.go

@@ -9,9 +9,7 @@ import (
 	"os"
 	"runtime/metrics"
 	"runtime/pprof"
-	"strconv"
 	"strings"
-	"syscall"
 	"time"
 
 	"github.com/ethereum/go-ethereum/log"
@@ -32,35 +30,13 @@ var EnabledExpensive = false
 // enablerFlags is the CLI flag names to use to enable metrics collections.
 var enablerFlags = []string{"metrics"}
 
-// enablerEnvVars is the env var names to use to enable metrics collections.
-var enablerEnvVars = []string{"GETH_METRICS"}
-
 // expensiveEnablerFlags is the CLI flag names to use to enable metrics collections.
 var expensiveEnablerFlags = []string{"metrics.expensive"}
 
-// expensiveEnablerEnvVars is the env var names to use to enable metrics collections.
-var expensiveEnablerEnvVars = []string{"GETH_METRICS_EXPENSIVE"}
-
 // Init enables or disables the metrics system. Since we need this to run before
 // any other code gets to create meters and timers, we'll actually do an ugly hack
 // and peek into the command line args for the metrics flag.
 func init() {
-	for _, enabler := range enablerEnvVars {
-		if val, found := syscall.Getenv(enabler); found && !Enabled {
-			if enable, _ := strconv.ParseBool(val); enable { // ignore error, flag parser will choke on it later
-				log.Info("Enabling metrics collection")
-				Enabled = true
-			}
-		}
-	}
-	for _, enabler := range expensiveEnablerEnvVars {
-		if val, found := syscall.Getenv(enabler); found && !EnabledExpensive {
-			if enable, _ := strconv.ParseBool(val); enable { // ignore error, flag parser will choke on it later
-				log.Info("Enabling expensive metrics collection")
-				EnabledExpensive = true
-			}
-		}
-	}
 	for _, arg := range os.Args {
 		flag := strings.TrimLeft(arg, "-")