Don't exit tablet server on reloading invalid ACL

This fixes potentially bringing down a tablet with an innocuous SIGHUP.

It also logs the fact it's reading the ACL file, to fix not getting any
feedback on SIGHUP.

#17139

go/vt/tableacl/tableacl.go

@@ -105,6 +105,7 @@ func (tacl *tableACL) init(configFile string, aclCB func()) error {
 	if configFile == "" {
 		return nil
 	}
+	log.Infof("Reading ACL file %v", configFile)
 	data, err := os.ReadFile(configFile)
 	if err != nil {
 		log.Infof("unable to read tableACL config file: %v  Error: %v", configFile, err)

go/vt/vttablet/tabletserver/tabletserver.go

@@ -383,7 +383,7 @@ func (tsv *TabletServer) InitACL(tableACLConfigFile string, enforceTableACLConfi
 	signal.Notify(sigChan, syscall.SIGHUP)
 	go func() {
 		for range sigChan {
-			tsv.initACL(tableACLConfigFile, enforceTableACLConfig)
+			tsv.initACL(tableACLConfigFile, false)
 		}
 	}()