Capture os signals to gracefully shutdown fission components (#2261)

- Currently, fission components don't handle shutdown signals.
So we don't get any to do the required cleanup before the fission process
exits. Adding signal capture process with cancelling context so
that all dependent processes stop working when the process gets term
signal.
- Set log level to error in otel shutdown function

Signed-off-by: Sanket Sudake <sanketsudake@gmail.com>

pkg/storagesvc/storagesvc.go

@@ -17,6 +17,7 @@ limitations under the License.
 package storagesvc
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"net/http"
@@ -221,7 +222,7 @@ func (ss *StorageService) Start(port int, openTracingEnabled bool) {
 }
 
 // Start runs storage service
-func Start(logger *zap.Logger, storage Storage, port int, openTracingEnabled bool) error {
+func Start(ctx context.Context, logger *zap.Logger, storage Storage, port int, openTracingEnabled bool) error {
 	enablePruner := true
 	// create a storage client
 	storageClient, err := MakeStowClient(logger, storage)
@@ -244,7 +245,7 @@ func Start(logger *zap.Logger, storage Storage, port int, openTracingEnabled boo
 		if err != nil {
 			return errors.Wrap(err, "Error creating archivePruner")
 		}
-		go pruner.Start()
+		go pruner.Start(ctx)
 	}
 
 	logger.Info("storage service started")