Distinguish manually submitted runs for periodic pagebench in grafana dashboard (#11079)

## Problem

Periodic pagebench workflow runs periodically from latest main commit
and also allows to dispatch it manually for a given commit hash to
bi-sect regressions.
However in the dashboards we can not distinguish manual runs from
periodic runs which makes it harder to follow the trend.

## Summary of changes

Send an additional flag commit type to the benchmark runner instance to
distinguish the run type.

Note: this needs a follow-up PR on the receiving side.

.github/workflows/periodic_pagebench.yml

@@ -78,8 +78,10 @@ jobs:
       run: |
         if [ -z "$INPUT_COMMIT_HASH" ]; then
           echo "COMMIT_HASH=$(curl -s https://api.github.com/repos/neondatabase/neon/commits/main | jq -r '.sha')" >> $GITHUB_ENV
+          echo "COMMIT_HASH_TYPE=latest" >> $GITHUB_ENV
         else
           echo "COMMIT_HASH=$INPUT_COMMIT_HASH" >> $GITHUB_ENV
+          echo "COMMIT_HASH_TYPE=manual" >> $GITHUB_ENV
         fi
 
     - name: Start Bench with run_id
@@ -89,7 +91,7 @@ jobs:
         -H 'accept: application/json' \
         -H 'Content-Type: application/json' \
         -H "Authorization: Bearer $API_KEY" \
-        -d "{\"neonRepoCommitHash\": \"${COMMIT_HASH}\"}"
+        -d "{\"neonRepoCommitHash\": \"${COMMIT_HASH}\", \"neonRepoCommitHashType\": \"${COMMIT_HASH_TYPE}\"}"
 
     - name: Poll Test Status
       id: poll_step