Promtail: Prevent logging errors on normal shutdown (#8988)

**What this PR does / why we need it**:
Since PR #4066 two messages are logged for the errors `ErrExpired` and
`EOF`, whereas nothing has been logged beforehand.

As `ErrExpired` is returned by the `JournalReader` after sending a
message to the `until` channel to signal a normal stop, this should not
be logged as an error.

CHANGELOG.md

@@ -17,8 +17,13 @@
 #### Promtail
 
 ##### Enhancements
+
 * [8474](https://github.com/grafana/loki/pull/8787) **andriikushch**: Promtail: Add a new target for the Azure Event Hubs
 
+##### Fixes
+
+* [8988](https://github.com/grafana/loki/pull/8988) **darxriggs**: Promtail: Prevent logging errors on normal shutdown.
+
 ## 2.8.0 (2023-03-??)
 
 #### Loki

clients/pkg/promtail/targets/journal/journaltarget.go

@@ -202,12 +202,16 @@ func journalTargetWithReader(
 		for {
 			err := t.r.Follow(until, io.Discard)
 			if err != nil {
-				level.Error(t.logger).Log("msg", "received error during sdjournal follow", "err", err.Error())
+				if err == sdjournal.ErrExpired {
+					return
+				}
 
-				if err == sdjournal.ErrExpired || err == syscall.EBADMSG || err == io.EOF {
+				if err == syscall.EBADMSG || err == io.EOF {
 					level.Error(t.logger).Log("msg", "unable to follow journal", "err", err.Error())
 					return
 				}
+
+				level.Error(t.logger).Log("msg", "received unexpected error while following the journal", "err", err.Error())
 			}
 
 			// prevent tight loop