exported timeseries from the datasink are not inheriting the metadata from the build spec

[filipecosta90]

Labels we already have:

benchmarks.redislabs.com:12011> ts.info  "ci.benchmarks.redislabs/by.branch/ci/redis/redis/redis-benchmark-full-suite-1Mkeys-100B/oss-standalone/benchmarks.api/rps/ZPOPMIN"
 1) totalSamples
 2) (integer) 4
 3) memoryUsage
 4) (integer) 4633
 5) firstTimestamp
 6) (integer) 1629306470835
 7) lastTimestamp
 8) (integer) 1629306632933
 9) retentionTime
10) (integer) 0
11) chunkCount
12) (integer) 1
13) maxSamplesPerChunk
14) (integer) 256
15) labels
16)  1) 1) "github_org"
        2) "redis"
     2) 1) "github_repo"
        2) "redis"
     3) 1) "github_org/github_repo"
        2) "redis/redis"
     4) 1) "deployment_type"
        2) "oss-standalone"
     5) 1) "triggering_env"
        2) "ci"
     6) 1) "branch"
        2) "benchmarks.api"
     7) 1) "test_name"
        2) "redis-benchmark-full-suite-1Mkeys-100B"
     8) 1) "metric"
        2) "rps"
     9) 1) "metric_name"
        2) "rps"
    10) 1) "metric_context_path"
        2) "ZPOPMIN"
    11) 1) "metric_jsonpath"
        2) "Tests.*.rps"
17) sourceKey
18) (nil)
19) rules
20) (empty array)

The labels that we want to add:

metadata:
  compiler: "icc"
  compiler_version: "2021.3.0 20210609"
  os: ubuntu18.04
  arch: amd64