qa-tests: fix rpc perf test workflow (#2139)

Author: mriccobene

.github/workflows/rpc-performance-tests.yml

@@ -75,7 +75,7 @@ jobs:
                pattern=$3
                sequence=$4
 
-               // clean temporary area
+               # clean temporary area
                cd ${{runner.workspace}}/rpc-tests/perf
                rm -rf ./reports/
 
@@ -127,7 +127,7 @@ jobs:
                   python3 $ERIGON_QA_PATH/test_system/qa-tests/rpc-tests/perf_hdr_analysis.py \
                     --test_name ${servers[i-1]}-$method \
                     --input_file ${{runner.workspace}}/rpc-tests/perf/reports/mainnet/result.json \
-                    --output_file ${{runner.workspace}}/rpc-tests/perf/reports/mainnet/${servers[i-1]}_$method_latency_hdr_analysis.pdf
+                    --output_file ${{runner.workspace}}/rpc-tests/perf/reports/mainnet/${servers[i-1]}-${method}-latency_hdr_analysis.pdf
                else
                   failed_test=1
                   cd ${{runner.workspace}}/silkworm