fix(integration): Fix flaky TestGRPCCompression by waiting for missin…

[yeya24]

…g metrics

Add e2e.WaitMissingMetrics option to the WaitSumMetricsWithOptions call so the test retries when cortex_ring_members is not yet exposed by the distributor, rather than failing immediately with 'metric not found'.

What this PR does:

Ports for container: e2e-cortex-test-querier Mapping: map[80:32810 9095:32811]
    grpc_compression_test.go:44: 
        	Error Trace:	/home/runner/work/cortex/cortex/integration/grpc_compression_test.go:44
        	Error:      	Received unexpected error:
        	            	metric not found
        	            	github.com/cortexproject/cortex/integration/e2e.init
        	            		<autogenerated>:1
        	            	runtime.doInit1
        	            		/opt/hostedtoolcache/go/1.26.2/arm64/src/runtime/proc.go:8103
        	            	runtime.doInit
        	            		/opt/hostedtoolcache/go/1.26.2/arm64/src/runtime/proc.go:8070
        	            	runtime.main
        	            		/opt/hostedtoolcache/go/1.26.2/arm64/src/runtime/proc.go:258
        	            	runtime.goexit
        	            		/opt/hostedtoolcache/go/1.26.2/arm64/src/runtime/asm_arm64.s:1447
        	            	metric=cortex_ring_members service=distributor
        	            	github.com/cortexproject/cortex/integration/e2e.(*HTTPService).SumMetrics
        	            		/home/runner/work/cortex/cortex/integration/e2e/service.go:655
        	            	github.com/cortexproject/cortex/integration/e2e.(*HTTPService).WaitSumMetricsWithOptions
        	            		/home/runner/work/cortex/cortex/integration/e2e/service.go:611
        	            	github.com/cortexproject/cortex/integration.TestGRPCCompression.func1
        	            		/home/runner/work/cortex/cortex/integration/grpc_compression_test.go:44
        	            	testing.tRunner
        	            		/opt/hostedtoolcache/go/1.26.2/arm64/src/testing/testing.go:2036
        	            	runtime.goexit
        	            		/opt/hostedtoolcache/go/1.26.2/arm64/src/runtime/asm_arm64.s:1447
        	Test:       	TestGRPCCompression/ingester_client/gzip

Which issue(s) this PR fixes:
Fixes #

Checklist

• Tests updated
• Documentation added
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]
• docs/configuration/v1-guarantees.md updated if this PR introduces experimental flags