Added Label Validation in SPM Integration Test (#6142)

## Which problem is this PR solving?
- Part of #5608 

## Description of the changes
- The changes include requesting metric with `groupByOperation` to get
labels along with `operation`. This is then compared with the expected
label set = `"operation service_name"`

## How was this change tested?
- jaeger/scripts/spm-integration-test.sh

## Checklist
- [x] I have read
https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
- [x] I have signed all commits
- [ ] I have added unit tests for the new functionality
- [x] I have run lint and test steps successfully
  - for `jaeger`: `make lint test`
  - for `jaeger-ui`: `yarn lint` and `yarn test`

---------

Signed-off-by: Alok Kumar Singh <dev.alok.singh123@gmail.com>
Co-authored-by: Yuri Shkuro <yurishkuro@users.noreply.github.com>

scripts/spm-integration-test.sh

@@ -111,6 +111,18 @@ validate_service_metrics() {
       echo "⏳ Expecting at least 4 non-zero data points"
       return 1
     fi
+
+     # Validate if labels are correct
+    local url="http://localhost:16686/api/metrics/calls?service=${service}&groupByOperation=true&endTs=&lookback=${fiveMinutes}&step=${fifteenSec}&ratePer=${oneMinute}"
+
+    local labels
+    labels=$(curl -s "$url" | jq -r '.metrics[0].labels[].name' | sort | tr '\n' ' ')
+    local exp_labels="operation service_name "
+
+    if [[ "$labels" != "$exp_labels" ]]; then
+      echo "❌ ERROR: Obtained labels: '$labels' are not same as expected labels: '$exp_labels'"
+      return 1
+    fi
     return 0
 }