Flaky Test_GetSeries

[bboreham]

Describe the bug
Test failed at: https://drone.grafana.net/grafana/loki/26733/3/5
and at https://drone.grafana.net/grafana/loki/26742/3/5
and https://drone.grafana.net/grafana/loki/26770/3/6

none of which change code near the failure.

To Reproduce
Unknown.

Expected behavior
CI tests either fail or pass consistently.

Environment:
Drone.

Screenshots, Promtail config, or terminal output

=== FAIL: pkg/storage/stores/series Test_GetSeries/foo{bar=~"beep|baz"}_/_v11_/_store (0.00s) test elide-stats-traces
    series_store_test.go:512: ========= Running query foo{bar=~"beep|baz"} with schema v11 test elide-stats-traces
    series_store_test.go:520:  test elide-stats-traces
        	Error Trace:	/src/loki/pkg/storage/stores/series/series_store_test.go:520 test elide-stats-traces
        	Error:      	Not equal:  test elide-stats-traces
        	            	expected: []labels.Labels{labels.Labels{labels.Label{Name:"bar", Value:"baz"}, labels.Label{Name:"flip", Value:"flop"}, labels.Label{Name:"toms", Value:"code"}}, labels.Labels{labels.Label{Name:"bar", Value:"beep"}, labels.Label{Name:"toms", Value:"code"}}} test elide-stats-traces
        	            	actual  : []labels.Labels{labels.Labels{labels.Label{Name:"bar", Value:"beep"}, labels.Label{Name:"toms", Value:"code"}}} test elide-stats-traces
        	            	 test elide-stats-traces
        	            	Diff: test elide-stats-traces
        	            	--- Expected test elide-stats-traces
        	            	+++ Actual test elide-stats-traces
        	            	@@ -1,16 +1,2 @@ test elide-stats-traces
        	            	-([]labels.Labels) (len=2) { test elide-stats-traces
        	            	- (labels.Labels) (len=3) { test elide-stats-traces
        	            	-  (labels.Label) { test elide-stats-traces
        	            	-   Name: (string) (len=3) "bar", test elide-stats-traces
        	            	-   Value: (string) (len=3) "baz" test elide-stats-traces
        	            	-  }, test elide-stats-traces
        	            	-  (labels.Label) { test elide-stats-traces
        	            	-   Name: (string) (len=4) "flip", test elide-stats-traces
        	            	-   Value: (string) (len=4) "flop" test elide-stats-traces
        	            	-  }, test elide-stats-traces
        	            	-  (labels.Label) { test elide-stats-traces
        	            	-   Name: (string) (len=4) "toms", test elide-stats-traces
        	            	-   Value: (string) (len=4) "code" test elide-stats-traces
        	            	-  } test elide-stats-traces
        	            	- }, test elide-stats-traces
        	            	+([]labels.Labels) (len=1) { test elide-stats-traces
        	            	  (labels.Labels) (len=2) { test elide-stats-traces
        	Test:       	Test_GetSeries/foo{bar=~"beep|baz"}_/_v11_/_store test elide-stats-traces
 test elide-stats-traces
=== FAIL: pkg/storage/stores/series Test_GetSeries (0.13s) test elide-stats-traces

[bboreham]

Perhaps related to #10310